diff --git a/.rubocop.yml b/.rubocop.yml
index 1abae8bb1..8b41dd5fd 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -17,7 +17,6 @@ Metrics/ClassLength:
     - 'app/builders/messages/facebook/message_builder.rb'
     - 'app/controllers/api/v1/accounts/contacts_controller.rb'
     - 'app/listeners/action_cable_listener.rb'
-    - 'app/models/conversation.rb'
 RSpec/ExampleLength:
   Max: 25
 Style/Documentation:
@@ -188,4 +187,3 @@ AllCops:
     - db/migrate/20200927135222_add_last_activity_at_to_conversation.rb
     - db/migrate/20210306170117_add_last_activity_at_to_contacts.rb
     - db/migrate/20220809104508_revert_cascading_indexes.rb
-    
diff --git a/app/controllers/api/v1/accounts/conversations/participants_controller.rb b/app/controllers/api/v1/accounts/conversations/participants_controller.rb
new file mode 100644
index 000000000..ebd02380f
--- /dev/null
+++ b/app/controllers/api/v1/accounts/conversations/participants_controller.rb
@@ -0,0 +1,41 @@
+class Api::V1::Accounts::Conversations::ParticipantsController < Api::V1::Accounts::Conversations::BaseController
+  def show
+    @participants = @conversation.conversation_participants
+  end
+
+  def create
+    ActiveRecord::Base.transaction do
+      @participants = participants_to_be_added_ids.map { |user_id| @conversation.conversation_participants.find_or_create_by(user_id: user_id) }
+    end
+  end
+
+  def update
+    ActiveRecord::Base.transaction do
+      participants_to_be_added_ids.each { |user_id| @conversation.conversation_participants.find_or_create_by(user_id: user_id) }
+      participants_to_be_removed_ids.each { |user_id| @conversation.conversation_participants.find_by(user_id: user_id)&.destroy }
+    end
+    @participants = @conversation.conversation_participants
+    render action: 'show'
+  end
+
+  def destroy
+    ActiveRecord::Base.transaction do
+      params[:user_ids].map { |user_id| @conversation.conversation_participants.find_by(user_id: user_id)&.destroy }
+    end
+    head :ok
+  end
+
+  private
+
+  def participants_to_be_added_ids
+    params[:user_ids] - current_participant_ids
+  end
+
+  def participants_to_be_removed_ids
+    current_participant_ids - params[:user_ids]
+  end
+
+  def current_participant_ids
+    @current_participant_ids ||= @conversation.conversation_participants.pluck(:user_id)
+  end
+end
diff --git a/app/finders/conversation_finder.rb b/app/finders/conversation_finder.rb
index b337e8458..9472dc623 100644
--- a/app/finders/conversation_finder.rb
+++ b/app/finders/conversation_finder.rb
@@ -97,6 +97,8 @@ class ConversationFinder
     when 'mention'
       conversation_ids = current_account.mentions.where(user: current_user).pluck(:conversation_id)
       @conversations = @conversations.where(id: conversation_ids)
+    when 'participating'
+      @conversations = current_user.participating_conversations.where(account_id: current_account.id)
     when 'unattended'
       @conversations = @conversations.where(first_reply_created_at: nil)
     end
diff --git a/app/mailers/agent_notifications/conversation_notifications_mailer.rb b/app/mailers/agent_notifications/conversation_notifications_mailer.rb
index c0f1f8630..95ed39b8d 100644
--- a/app/mailers/agent_notifications/conversation_notifications_mailer.rb
+++ b/app/mailers/agent_notifications/conversation_notifications_mailer.rb
@@ -42,6 +42,18 @@ class AgentNotifications::ConversationNotificationsMailer < ApplicationMailer
     send_mail_with_liquid(to: @agent.email, subject: subject) and return
   end
 
+  def participating_conversation_new_message(message, agent)
+    return unless smtp_config_set_or_development?
+    # Don't spam with email notifications if agent is online
+    return if ::OnlineStatusTracker.get_presence(message.account_id, 'User', agent.id)
+
+    @agent = agent
+    @conversation = message.conversation
+    subject = "#{@agent.available_name}, New message in your participating conversation [ID - #{@conversation.display_id}]."
+    @action_url = app_account_conversation_url(account_id: @conversation.account_id, id: @conversation.display_id)
+    send_mail_with_liquid(to: @agent.email, subject: subject) and return
+  end
+
   private
 
   def liquid_droppables
diff --git a/app/models/concerns/assignment_handler.rb b/app/models/concerns/assignment_handler.rb
index dde962ba1..cf4ef123e 100644
--- a/app/models/concerns/assignment_handler.rb
+++ b/app/models/concerns/assignment_handler.rb
@@ -4,7 +4,7 @@ module AssignmentHandler
 
   included do
     before_save :ensure_assignee_is_from_team
-    after_commit :notify_assignment_change, :process_assignment_activities
+    after_commit :notify_assignment_change, :process_assignment_changes
   end
 
   private
@@ -36,6 +36,11 @@ module AssignmentHandler
     end
   end
 
+  def process_assignment_changes
+    process_assignment_activities
+    process_participant_assignment
+  end
+
   def process_assignment_activities
     user_name = Current.user.name if Current.user.present?
     if saved_change_to_team_id?
@@ -44,4 +49,10 @@ module AssignmentHandler
       create_assignee_change_activity(user_name)
     end
   end
+
+  def process_participant_assignment
+    return unless saved_change_to_assignee_id? && assignee_id.present?
+
+    conversation_participants.find_or_create_by!(user_id: assignee_id)
+  end
 end
diff --git a/app/models/concerns/user_attribute_helpers.rb b/app/models/concerns/user_attribute_helpers.rb
new file mode 100644
index 000000000..32ff026ac
--- /dev/null
+++ b/app/models/concerns/user_attribute_helpers.rb
@@ -0,0 +1,53 @@
+module UserAttributeHelpers
+  extend ActiveSupport::Concern
+
+  def available_name
+    self[:display_name].presence || name
+  end
+
+  def availability_status
+    current_account_user&.availability_status
+  end
+
+  def auto_offline
+    current_account_user&.auto_offline
+  end
+
+  def inviter
+    current_account_user&.inviter
+  end
+
+  def active_account_user
+    account_users.order(active_at: :desc)&.first
+  end
+
+  def current_account_user
+    # We want to avoid subsequent queries in case where the association is preloaded.
+    # using where here will trigger n+1 queries.
+    account_users.find { |ac_usr| ac_usr.account_id == Current.account.id } if Current.account
+  end
+
+  def account
+    current_account_user&.account
+  end
+
+  def administrator?
+    current_account_user&.administrator?
+  end
+
+  def agent?
+    current_account_user&.agent?
+  end
+
+  def role
+    current_account_user&.role
+  end
+
+  # Used internally for Chatwoot in Chatwoot
+  def hmac_identifier
+    hmac_key = GlobalConfig.get('CHATWOOT_INBOX_HMAC_KEY')['CHATWOOT_INBOX_HMAC_KEY']
+    return OpenSSL::HMAC.hexdigest('sha256', hmac_key, email) if hmac_key.present?
+
+    ''
+  end
+end
diff --git a/app/models/conversation.rb b/app/models/conversation.rb
index e2c1d43a4..5d40ab513 100644
--- a/app/models/conversation.rb
+++ b/app/models/conversation.rb
@@ -86,6 +86,7 @@ class Conversation < ApplicationRecord
   has_many :mentions, dependent: :destroy_async
   has_many :messages, dependent: :destroy_async, autosave: true
   has_one :csat_survey_response, dependent: :destroy_async
+  has_many :conversation_participants, dependent: :destroy_async
   has_many :notifications, as: :primary_actor, dependent: :destroy_async
 
   before_save :ensure_snooze_until_reset
diff --git a/app/models/conversation_participant.rb b/app/models/conversation_participant.rb
new file mode 100644
index 000000000..830eb7baa
--- /dev/null
+++ b/app/models/conversation_participant.rb
@@ -0,0 +1,41 @@
+# == Schema Information
+#
+# Table name: conversation_participants
+#
+#  id              :bigint           not null, primary key
+#  created_at      :datetime         not null
+#  updated_at      :datetime         not null
+#  account_id      :bigint           not null
+#  conversation_id :bigint           not null
+#  user_id         :bigint           not null
+#
+# Indexes
+#
+#  index_conversation_participants_on_account_id                   (account_id)
+#  index_conversation_participants_on_conversation_id              (conversation_id)
+#  index_conversation_participants_on_user_id                      (user_id)
+#  index_conversation_participants_on_user_id_and_conversation_id  (user_id,conversation_id) UNIQUE
+#
+class ConversationParticipant < ApplicationRecord
+  validates :account_id, presence: true
+  validates :conversation_id, presence: true
+  validates :user_id, presence: true
+  validates :user_id, uniqueness: { scope: [:conversation_id] }
+  validate :ensure_inbox_access
+
+  belongs_to :account
+  belongs_to :conversation
+  belongs_to :user
+
+  before_validation :ensure_account_id
+
+  private
+
+  def ensure_account_id
+    self.account_id = conversation&.account_id
+  end
+
+  def ensure_inbox_access
+    errors.add(:user, 'must have inbox access') if conversation && conversation.inbox.assignable_agents.exclude?(user)
+  end
+end
diff --git a/app/models/notification.rb b/app/models/notification.rb
index 78591b96a..681203710 100644
--- a/app/models/notification.rb
+++ b/app/models/notification.rb
@@ -34,7 +34,8 @@ class Notification < ApplicationRecord
     conversation_creation: 1,
     conversation_assignment: 2,
     assigned_conversation_new_message: 3,
-    conversation_mention: 4
+    conversation_mention: 4,
+    participating_conversation_new_message: 5
   }.freeze
 
   enum notification_type: NOTIFICATION_TYPES
@@ -94,7 +95,7 @@ class Notification < ApplicationRecord
       I18n.t('notifications.notification_title.conversation_creation', display_id: primary_actor.display_id, inbox_name: primary_actor.inbox.name)
     when 'conversation_assignment'
       I18n.t('notifications.notification_title.conversation_assignment', display_id: primary_actor.display_id)
-    when 'assigned_conversation_new_message'
+    when 'assigned_conversation_new_message', 'participating_conversation_new_message'
       I18n.t(
         'notifications.notification_title.assigned_conversation_new_message',
         display_id: conversation.display_id,
@@ -109,7 +110,11 @@ class Notification < ApplicationRecord
   # rubocop:enable Metrics/CyclomaticComplexity
 
   def conversation
-    return primary_actor.conversation if %w[assigned_conversation_new_message conversation_mention].include? notification_type
+    return primary_actor.conversation if %w[
+      assigned_conversation_new_message
+      participating_conversation_new_message
+      conversation_mention
+    ].include? notification_type
 
     primary_actor
   end
diff --git a/app/models/user.rb b/app/models/user.rb
index 3094990d5..a908bd1f8 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -48,6 +48,7 @@ class User < ApplicationRecord
   include Rails.application.routes.url_helpers
   include Reportable
   include SsoAuthenticatable
+  include UserAttributeHelpers
 
   devise :database_authenticatable,
          :registerable,
@@ -76,6 +77,8 @@ class User < ApplicationRecord
   has_many :assigned_conversations, foreign_key: 'assignee_id', class_name: 'Conversation', dependent: :nullify
   alias_attribute :conversations, :assigned_conversations
   has_many :csat_survey_responses, foreign_key: 'assigned_agent_id', dependent: :nullify
+  has_many :conversation_participants, dependent: :destroy_async
+  has_many :participating_conversations, through: :conversation_participants, source: :conversation
 
   has_many :inbox_members, dependent: :destroy_async
   has_many :inboxes, through: :inbox_members, source: :inbox
@@ -110,60 +113,10 @@ class User < ApplicationRecord
     self.uid = email
   end
 
-  def active_account_user
-    account_users.order(active_at: :desc)&.first
-  end
-
-  def current_account_user
-    # We want to avoid subsequent queries in case where the association is preloaded.
-    # using where here will trigger n+1 queries.
-    account_users.find { |ac_usr| ac_usr.account_id == Current.account.id } if Current.account
-  end
-
-  def available_name
-    self[:display_name].presence || name
-  end
-
-  # Used internally for Chatwoot in Chatwoot
-  def hmac_identifier
-    hmac_key = GlobalConfig.get('CHATWOOT_INBOX_HMAC_KEY')['CHATWOOT_INBOX_HMAC_KEY']
-    return OpenSSL::HMAC.hexdigest('sha256', hmac_key, email) if hmac_key.present?
-
-    ''
-  end
-
-  def account
-    current_account_user&.account
-  end
-
   def assigned_inboxes
     administrator? ? Current.account.inboxes : inboxes.where(account_id: Current.account.id)
   end
 
-  def administrator?
-    current_account_user&.administrator?
-  end
-
-  def agent?
-    current_account_user&.agent?
-  end
-
-  def role
-    current_account_user&.role
-  end
-
-  def availability_status
-    current_account_user&.availability_status
-  end
-
-  def auto_offline
-    current_account_user&.auto_offline
-  end
-
-  def inviter
-    current_account_user&.inviter
-  end
-
   def serializable_hash(options = nil)
     super(options).merge(confirmed: confirmed?)
   end
diff --git a/app/services/messages/mention_service.rb b/app/services/messages/mention_service.rb
index c7b81213b..aa8cbfce2 100644
--- a/app/services/messages/mention_service.rb
+++ b/app/services/messages/mention_service.rb
@@ -9,6 +9,7 @@ class Messages::MentionService
 
     Conversations::UserMentionJob.perform_later(validated_mentioned_ids, message.conversation.id, message.account.id)
     generate_notifications_for_mentions(validated_mentioned_ids)
+    add_mentioned_users_as_participants(validated_mentioned_ids)
   end
 
   private
@@ -38,4 +39,10 @@ class Messages::MentionService
       ).perform
     end
   end
+
+  def add_mentioned_users_as_participants(validated_mentioned_ids)
+    validated_mentioned_ids.each do |user_id|
+      message.conversation.conversation_participants.find_or_create_by!(user_id: user_id)
+    end
+  end
 end
diff --git a/app/services/messages/new_message_notification_service.rb b/app/services/messages/new_message_notification_service.rb
index 2a500fbac..f292ef19a 100644
--- a/app/services/messages/new_message_notification_service.rb
+++ b/app/services/messages/new_message_notification_service.rb
@@ -4,6 +4,7 @@ class Messages::NewMessageNotificationService
   def perform
     return unless message.notifiable?
 
+    notify_participating_users
     notify_conversation_assignee
   end
 
@@ -11,8 +12,23 @@ class Messages::NewMessageNotificationService
 
   delegate :conversation, :sender, :account, to: :message
 
+  def notify_participating_users
+    participating_users = conversation.conversation_participants.map(&:user)
+    participating_users -= [sender] if sender.is_a?(User)
+
+    participating_users.uniq.each do |participant|
+      NotificationBuilder.new(
+        notification_type: 'participating_conversation_new_message',
+        user: participant,
+        account: account,
+        primary_actor: message
+      ).perform
+    end
+  end
+
   def notify_conversation_assignee
     return if conversation.assignee.blank?
+    return if assignee_already_notified_via_participation?
     return if conversation.assignee == sender
 
     NotificationBuilder.new(
@@ -22,4 +38,13 @@ class Messages::NewMessageNotificationService
       primary_actor: message
     ).perform
   end
+
+  def assignee_already_notified_via_participation?
+    return unless conversation.conversation_participants.map(&:user).include?(conversation.assignee)
+
+    # check whether participation notifcation is disabled for assignee
+    notification_setting = conversation.assignee.notification_settings.find_by(account_id: account.id)
+    notification_setting.public_send(:email_participating_conversation_new_message?) || notification_setting
+      .public_send(:push_participating_conversation_new_message?)
+  end
 end
diff --git a/app/views/api/v1/accounts/conversations/participants/create.json.jbuilder b/app/views/api/v1/accounts/conversations/participants/create.json.jbuilder
new file mode 100644
index 000000000..5de95847d
--- /dev/null
+++ b/app/views/api/v1/accounts/conversations/participants/create.json.jbuilder
@@ -0,0 +1,3 @@
+json.array! @participants do |participant|
+  json.partial! 'api/v1/models/agent', format: :json, resource: participant.user
+end
diff --git a/app/views/api/v1/accounts/conversations/participants/show.json.jbuilder b/app/views/api/v1/accounts/conversations/participants/show.json.jbuilder
new file mode 100644
index 000000000..5de95847d
--- /dev/null
+++ b/app/views/api/v1/accounts/conversations/participants/show.json.jbuilder
@@ -0,0 +1,3 @@
+json.array! @participants do |participant|
+  json.partial! 'api/v1/models/agent', format: :json, resource: participant.user
+end
diff --git a/app/views/api/v1/accounts/notifications/index.json.jbuilder b/app/views/api/v1/accounts/notifications/index.json.jbuilder
index e715d5ada..4e881fe1a 100644
--- a/app/views/api/v1/accounts/notifications/index.json.jbuilder
+++ b/app/views/api/v1/accounts/notifications/index.json.jbuilder
@@ -11,7 +11,11 @@ json.data do
       json.notification_type notification.notification_type
       json.push_message_title notification.push_message_title
       # TODO: front end assumes primary actor to be conversation. should fix in future
-      if %w[assigned_conversation_new_message conversation_mention].include? notification.notification_type
+      if %w[
+        assigned_conversation_new_message
+        participating_conversation_new_message
+        conversation_mention
+      ].include? notification.notification_type
         json.primary_actor_type 'Conversation'
         json.primary_actor_id notification.conversation.id
         json.primary_actor notification.conversation.push_event_data
diff --git a/app/views/mailers/agent_notifications/conversation_notifications_mailer/participating_conversation_new_message.liquid b/app/views/mailers/agent_notifications/conversation_notifications_mailer/participating_conversation_new_message.liquid
new file mode 100644
index 000000000..977b15b6a
--- /dev/null
+++ b/app/views/mailers/agent_notifications/conversation_notifications_mailer/participating_conversation_new_message.liquid
@@ -0,0 +1,5 @@
+<p>Hi {{user.available_name}},</p>
+
+<p>You have received a new message in a conversation you are participating.</p>
+
+<p>Click <a href="{{action_url}}">here</a> to get cracking.</p>
diff --git a/config/routes.rb b/config/routes.rb
index 141e9a0dd..02f1e4991 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -77,6 +77,7 @@ Rails.application.routes.draw do
               resources :messages, only: [:index, :create, :destroy]
               resources :assignments, only: [:create]
               resources :labels, only: [:create, :index]
+              resource :participants, only: [:show, :create, :update, :destroy]
               resource :direct_uploads, only: [:create]
             end
             member do
diff --git a/db/migrate/20220808193420_add_conversation_participants.rb b/db/migrate/20220808193420_add_conversation_participants.rb
new file mode 100644
index 000000000..a130a5e01
--- /dev/null
+++ b/db/migrate/20220808193420_add_conversation_participants.rb
@@ -0,0 +1,11 @@
+class AddConversationParticipants < ActiveRecord::Migration[6.1]
+  def change
+    create_table 'conversation_participants', force: :cascade do |t|
+      t.references :account, null: false
+      t.references :user, null: false
+      t.references :conversation, null: false
+      t.datetime 'created_at', precision: 6, null: false
+      t.datetime 'updated_at', precision: 6, null: false
+    end
+  end
+end
diff --git a/db/migrate/20230118155353_add_unique_index_to_conversation_participants.rb b/db/migrate/20230118155353_add_unique_index_to_conversation_participants.rb
new file mode 100644
index 000000000..cf47c6ea8
--- /dev/null
+++ b/db/migrate/20230118155353_add_unique_index_to_conversation_participants.rb
@@ -0,0 +1,5 @@
+class AddUniqueIndexToConversationParticipants < ActiveRecord::Migration[6.1]
+  def change
+    add_index :conversation_participants, [:user_id, :conversation_id], unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index c85a598cd..68284421c 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -388,6 +388,18 @@ ActiveRecord::Schema.define(version: 2023_02_09_033203) do
     t.index ["phone_number", "account_id"], name: "index_contacts_on_phone_number_and_account_id"
   end
 
+  create_table "conversation_participants", force: :cascade do |t|
+    t.bigint "account_id", null: false
+    t.bigint "user_id", null: false
+    t.bigint "conversation_id", null: false
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["account_id"], name: "index_conversation_participants_on_account_id"
+    t.index ["conversation_id"], name: "index_conversation_participants_on_conversation_id"
+    t.index ["user_id", "conversation_id"], name: "index_conversation_participants_on_user_id_and_conversation_id", unique: true
+    t.index ["user_id"], name: "index_conversation_participants_on_user_id"
+  end
+
   create_table "conversations", id: :serial, force: :cascade do |t|
     t.integer "account_id", null: false
     t.integer "inbox_id", null: false
diff --git a/spec/controllers/api/v1/accounts/bulk_actions_controller_spec.rb b/spec/controllers/api/v1/accounts/bulk_actions_controller_spec.rb
index e6128ca82..8306ec539 100644
--- a/spec/controllers/api/v1/accounts/bulk_actions_controller_spec.rb
+++ b/spec/controllers/api/v1/accounts/bulk_actions_controller_spec.rb
@@ -12,6 +12,10 @@ RSpec.describe 'Api::V1::Accounts::BulkActionsController', type: :request do
     create(:conversation, account_id: account.id, status: :open, team_id: team_1.id)
     create(:conversation, account_id: account.id, status: :open)
     create(:conversation, account_id: account.id, status: :open)
+    Conversation.all.each do |conversation|
+      create(:inbox_member, inbox: conversation.inbox, user: agent_1)
+      create(:inbox_member, inbox: conversation.inbox, user: agent_2)
+    end
   end
 
   describe 'POST /api/v1/accounts/{account.id}/bulk_action' do
diff --git a/spec/controllers/api/v1/accounts/conversations/assignments_controller_spec.rb b/spec/controllers/api/v1/accounts/conversations/assignments_controller_spec.rb
index dbe19690a..a4e9d8cb0 100644
--- a/spec/controllers/api/v1/accounts/conversations/assignments_controller_spec.rb
+++ b/spec/controllers/api/v1/accounts/conversations/assignments_controller_spec.rb
@@ -56,8 +56,8 @@ RSpec.describe 'Conversation Assignment API', type: :request do
       let(:agent) { create(:user, account: account, role: :agent) }
 
       before do
-        conversation.update!(assignee: agent)
         create(:inbox_member, inbox: conversation.inbox, user: agent)
+        conversation.update!(assignee: agent)
       end
 
       it 'unassigns the assignee from the conversation' do
diff --git a/spec/controllers/api/v1/accounts/conversations/participants_controller_spec.rb b/spec/controllers/api/v1/accounts/conversations/participants_controller_spec.rb
new file mode 100644
index 000000000..6238314ab
--- /dev/null
+++ b/spec/controllers/api/v1/accounts/conversations/participants_controller_spec.rb
@@ -0,0 +1,142 @@
+require 'rails_helper'
+
+RSpec.describe 'Conversation Participants API', type: :request do
+  let(:account) { create(:account) }
+  let(:conversation) { create(:conversation, account: account) }
+  let(:agent) { create(:user, account: account, role: :agent) }
+
+  before do
+    create(:inbox_member, inbox: conversation.inbox, user: agent)
+  end
+
+  describe 'GET /api/v1/accounts/{account.id}/conversations/<id>/paricipants' do
+    context 'when it is an unauthenticated user' do
+      it 'returns unauthorized' do
+        get api_v1_account_conversation_participants_url(account_id: account.id, conversation_id: conversation.display_id)
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when it is an authenticated user with access to the conversation' do
+      let(:participant1) { create(:user, account: account, role: :agent) }
+      let(:participant2) { create(:user, account: account, role: :agent) }
+
+      before do
+        create(:inbox_member, inbox: conversation.inbox, user: participant1)
+        create(:inbox_member, inbox: conversation.inbox, user: participant2)
+      end
+
+      it 'returns all the partipants for the conversation' do
+        create(:conversation_participant, conversation: conversation, user: participant1)
+        create(:conversation_participant, conversation: conversation, user: participant2)
+        get api_v1_account_conversation_participants_url(account_id: account.id, conversation_id: conversation.display_id),
+            headers: agent.create_new_auth_token,
+            as: :json
+
+        expect(response).to have_http_status(:success)
+        expect(response.body).to include(participant1.email)
+        expect(response.body).to include(participant2.email)
+      end
+    end
+  end
+
+  describe 'POST /api/v1/accounts/{account.id}/conversations/<id>/participants' do
+    context 'when it is an unauthenticated user' do
+      it 'returns unauthorized' do
+        post api_v1_account_conversation_participants_url(account_id: account.id, conversation_id: conversation.display_id)
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when it is an authenticated user' do
+      let(:participant) { create(:user, account: account, role: :agent) }
+
+      before do
+        create(:inbox_member, inbox: conversation.inbox, user: participant)
+      end
+
+      it 'creates a new participants when its authorized agent' do
+        params = { user_ids: [participant.id] }
+
+        expect(conversation.conversation_participants.count).to eq(0)
+        post api_v1_account_conversation_participants_url(account_id: account.id, conversation_id: conversation.display_id),
+             params: params,
+             headers: agent.create_new_auth_token,
+             as: :json
+
+        expect(response).to have_http_status(:success)
+        expect(response.body).to include(participant.email)
+        expect(conversation.conversation_participants.count).to eq(1)
+      end
+    end
+  end
+
+  describe 'PUT /api/v1/accounts/{account.id}/conversations/<id>/participants' do
+    context 'when it is an unauthenticated user' do
+      it 'returns unauthorized' do
+        put api_v1_account_conversation_participants_url(account_id: account.id, conversation_id: conversation.display_id)
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when it is an authenticated user' do
+      let(:participant) { create(:user, account: account, role: :agent) }
+      let(:participant_to_be_added) { create(:user, account: account, role: :agent) }
+      let(:participant_to_be_removed) { create(:user, account: account, role: :agent) }
+
+      before do
+        create(:inbox_member, inbox: conversation.inbox, user: participant)
+        create(:inbox_member, inbox: conversation.inbox, user: participant_to_be_added)
+        create(:inbox_member, inbox: conversation.inbox, user: participant_to_be_removed)
+      end
+
+      it 'updates participants when its authorized agent' do
+        params = { user_ids: [participant.id, participant_to_be_added.id] }
+        create(:conversation_participant, conversation: conversation, user: participant)
+        create(:conversation_participant, conversation: conversation, user: participant_to_be_removed)
+
+        expect(conversation.conversation_participants.count).to eq(2)
+        put api_v1_account_conversation_participants_url(account_id: account.id, conversation_id: conversation.display_id),
+            params: params,
+            headers: agent.create_new_auth_token,
+            as: :json
+
+        expect(response).to have_http_status(:success)
+        expect(response.body).to include(participant.email)
+        expect(response.body).to include(participant_to_be_added.email)
+        expect(conversation.conversation_participants.count).to eq(2)
+      end
+    end
+  end
+
+  describe 'DELETE /api/v1/accounts/{account.id}/conversations/<id>/participants' do
+    context 'when it is an unauthenticated user' do
+      it 'returns unauthorized' do
+        delete api_v1_account_conversation_participants_url(account_id: account.id, conversation_id: conversation.display_id)
+        expect(response).to have_http_status(:unauthorized)
+      end
+    end
+
+    context 'when it is an authenticated user' do
+      let(:participant) { create(:user, account: account, role: :agent) }
+
+      before do
+        create(:inbox_member, inbox: conversation.inbox, user: participant)
+      end
+
+      it 'deletes participants when its authorized agent' do
+        params = { user_ids: [participant.id] }
+        create(:conversation_participant, conversation: conversation, user: participant)
+
+        expect(conversation.conversation_participants.count).to eq(1)
+        delete api_v1_account_conversation_participants_url(account_id: account.id, conversation_id: conversation.display_id),
+               params: params,
+               headers: agent.create_new_auth_token,
+               as: :json
+
+        expect(response).to have_http_status(:success)
+        expect(conversation.conversation_participants.count).to eq(0)
+      end
+    end
+  end
+end
diff --git a/spec/controllers/api/v2/accounts/report_controller_spec.rb b/spec/controllers/api/v2/accounts/report_controller_spec.rb
index 134a61220..1d5be3592 100644
--- a/spec/controllers/api/v2/accounts/report_controller_spec.rb
+++ b/spec/controllers/api/v2/accounts/report_controller_spec.rb
@@ -111,11 +111,11 @@ RSpec.describe 'Reports API', type: :request do
     context 'when an agent1 associated to conversation having first reply from agent2' do
       let(:listener) { ReportingEventListener.instance }
       let(:account) { create(:account) }
-      let(:admin) { create(:user, account: account, role: :administrator) }
+      let(:agent2) { create(:user, account: account, role: :agent) }
 
       it 'returns unattended conversation count zero for agent1' do
-        agent1 = create(:user, account: account, role: :agent)
-        agent2 = create(:user, account: account, role: :agent)
+        create(:inbox_member, user: agent, inbox: inbox)
+        create(:inbox_member, user: agent2, inbox: inbox)
         conversation = create(:conversation, account: account,
                                              inbox: inbox, assignee: agent2)
 
@@ -129,7 +129,7 @@ RSpec.describe 'Reports API', type: :request do
         event = Events::Base.new('first.reply.created', Time.zone.now, message: first_reply_message)
         listener.first_reply_created(event)
 
-        conversation.assignee_id = agent1.id
+        conversation.assignee_id = agent.id
         conversation.save!
 
         get "/api/v2/accounts/#{account.id}/reports/conversations",
@@ -140,7 +140,7 @@ RSpec.describe 'Reports API', type: :request do
             as: :json
 
         json_response = JSON.parse(response.body)
-        user_metrics = json_response.find { |item| item['name'] == agent1[:name] }
+        user_metrics = json_response.find { |item| item['name'] == agent[:name] }
         expect(user_metrics.present?).to be true
 
         expect(user_metrics['metric']['open']).to eq(1)
diff --git a/spec/factories/conversation_participants.rb b/spec/factories/conversation_participants.rb
new file mode 100644
index 000000000..9b10d2fe5
--- /dev/null
+++ b/spec/factories/conversation_participants.rb
@@ -0,0 +1,13 @@
+FactoryBot.define do
+  factory :conversation_participant do
+    conversation
+    account
+
+    before(:build) do |conversation|
+      if conversation.user.blank?
+        conversation.user = create(:user, account: conversation.account)
+        create(:inbox_member, user: conversation.user, inbox: conversation.conversation.inbox)
+      end
+    end
+  end
+end
diff --git a/spec/jobs/bulk_actions_job_spec.rb b/spec/jobs/bulk_actions_job_spec.rb
index 80784a6db..2051c69b2 100644
--- a/spec/jobs/bulk_actions_job_spec.rb
+++ b/spec/jobs/bulk_actions_job_spec.rb
@@ -15,6 +15,12 @@ RSpec.describe BulkActionsJob, type: :job do
   let!(:conversation_2) { create(:conversation, account_id: account.id, status: :open) }
   let!(:conversation_3) { create(:conversation, account_id: account.id, status: :open) }
 
+  before do
+    Conversation.all.each do |conversation|
+      create(:inbox_member, inbox: conversation.inbox, user: agent)
+    end
+  end
+
   it 'enqueues the job' do
     expect { job }.to have_enqueued_job(described_class)
       .with(account: account, params: params, user: agent)
diff --git a/spec/mailers/agent_notifications/conversation_notifications_mailer_spec.rb b/spec/mailers/agent_notifications/conversation_notifications_mailer_spec.rb
index a4e00204d..6b102d566 100644
--- a/spec/mailers/agent_notifications/conversation_notifications_mailer_spec.rb
+++ b/spec/mailers/agent_notifications/conversation_notifications_mailer_spec.rb
@@ -87,4 +87,22 @@ RSpec.describe AgentNotifications::ConversationNotificationsMailer, type: :maile
       expect(mail).to be_nil
     end
   end
+
+  describe 'participating_conversation_new_message' do
+    let(:message) { create(:message, conversation: conversation, account: account) }
+    let(:mail) { described_class.with(account: account).participating_conversation_new_message(message, agent).deliver_now }
+
+    it 'renders the subject' do
+      expect(mail.subject).to eq("#{agent.available_name}, New message in your participating conversation [ID - #{message.conversation.display_id}].")
+    end
+
+    it 'renders the receiver email' do
+      expect(mail.to).to eq([agent.email])
+    end
+
+    it 'will not send email if agent is online' do
+      ::OnlineStatusTracker.update_presence(conversation.account.id, 'User', agent.id)
+      expect(mail).to be_nil
+    end
+  end
 end
diff --git a/spec/models/concerns/assignment_handler_shared.rb b/spec/models/concerns/assignment_handler_shared.rb
index 816351248..55951cd99 100644
--- a/spec/models/concerns/assignment_handler_shared.rb
+++ b/spec/models/concerns/assignment_handler_shared.rb
@@ -73,6 +73,10 @@ shared_examples_for 'assignment_handler' do
     end
     let(:assignment_mailer) { instance_double(AgentNotifications::ConversationNotificationsMailer, deliver: true) }
 
+    before do
+      create(:inbox_member, user: agent, inbox: conversation.inbox)
+    end
+
     it 'assigns the agent to conversation' do
       expect(update_assignee).to be(true)
       expect(conversation.reload.assignee).to eq(agent)
@@ -85,6 +89,10 @@ shared_examples_for 'assignment_handler' do
       expect(update_assignee).to be(true)
     end
 
+    it 'adds assignee to conversation participants' do
+      expect { update_assignee }.to change { conversation.conversation_participants.count }.by(1)
+    end
+
     context 'when agent is current user' do
       before do
         Current.user = agent
diff --git a/spec/models/conversation_participants_spec.rb b/spec/models/conversation_participants_spec.rb
new file mode 100644
index 000000000..6e0fe7504
--- /dev/null
+++ b/spec/models/conversation_participants_spec.rb
@@ -0,0 +1,32 @@
+require 'rails_helper'
+
+RSpec.describe ConversationParticipant, type: :model do
+  context 'with validations' do
+    it { is_expected.to validate_presence_of(:account_id) }
+    it { is_expected.to validate_presence_of(:conversation_id) }
+    it { is_expected.to validate_presence_of(:user_id) }
+  end
+
+  describe 'associations' do
+    it { is_expected.to belong_to(:account) }
+    it { is_expected.to belong_to(:conversation) }
+    it { is_expected.to belong_to(:user) }
+  end
+
+  describe 'validations' do
+    it 'ensure account is present' do
+      conversation = create(:conversation)
+      conversation_participant = build(:conversation_participant, conversation: conversation, account_id: nil)
+      conversation_participant.valid?
+      expect(conversation_participant.account_id).to eq(conversation.account_id)
+    end
+
+    it 'throws error if inbox member does not belongs to account' do
+      conversation = create(:conversation)
+      user = create(:user, account: conversation.account)
+      participant = build(:conversation_participant, user: user, conversation: conversation)
+      expect { participant.save! }.to raise_error(ActiveRecord::RecordInvalid)
+      expect(participant.errors.messages[:user]).to eq(['must have inbox access'])
+    end
+  end
+end
diff --git a/spec/models/conversation_spec.rb b/spec/models/conversation_spec.rb
index e27eda55c..aca21e843 100644
--- a/spec/models/conversation_spec.rb
+++ b/spec/models/conversation_spec.rb
@@ -105,6 +105,8 @@ RSpec.describe Conversation, type: :model do
     let(:label) { create(:label, account: account) }
 
     before do
+      create(:inbox_member, user: old_assignee, inbox: conversation.inbox)
+      create(:inbox_member, user: new_assignee, inbox: conversation.inbox)
       allow(Rails.configuration.dispatcher).to receive(:dispatch)
       Current.user = old_assignee
     end
diff --git a/spec/models/notification_spec.rb b/spec/models/notification_spec.rb
index e3584d182..15894d2d7 100644
--- a/spec/models/notification_spec.rb
+++ b/spec/models/notification_spec.rb
@@ -51,6 +51,14 @@ RSpec.describe Notification do
       expect(notification.push_message_title).to eq "[New message] - ##{notification.conversation.display_id} "
     end
 
+    it 'returns appropriate title suited for the notification type participating_conversation_new_message' do
+      message = create(:message, sender: create(:user), content: Faker::Lorem.paragraphs(number: 2))
+      notification = create(:notification, notification_type: 'participating_conversation_new_message', primary_actor: message)
+
+      expect(notification.push_message_title).to eq "[New message] - ##{notification.conversation.display_id} \
+#{message.content.truncate_words(10)}"
+    end
+
     it 'returns appropriate title suited for the notification type conversation_mention' do
       message = create(:message, sender: create(:user), content: 'Hey [@John](mention://user/1/john), can you check this ticket?')
       notification = create(:notification, notification_type: 'conversation_mention', primary_actor: message, secondary_actor: message.sender)
diff --git a/spec/services/auto_assignment/agent_assignment_service_spec.rb b/spec/services/auto_assignment/agent_assignment_service_spec.rb
index 00f813d33..83790dc28 100644
--- a/spec/services/auto_assignment/agent_assignment_service_spec.rb
+++ b/spec/services/auto_assignment/agent_assignment_service_spec.rb
@@ -16,6 +16,7 @@ RSpec.describe AutoAssignment::AgentAssignmentService do
   end
 
   before do
+    inbox_members.each { |inbox_member| create(:account_user, account: account, user: inbox_member.user) }
     allow(::OnlineStatusTracker).to receive(:get_available_users).and_return(online_users)
   end
 
diff --git a/spec/services/messages/mention_service_spec.rb b/spec/services/messages/mention_service_spec.rb
index e381883bf..21484ab13 100644
--- a/spec/services/messages/mention_service_spec.rb
+++ b/spec/services/messages/mention_service_spec.rb
@@ -61,5 +61,10 @@ describe Messages::MentionService do
                                                               account: account,
                                                               primary_actor: message)
     end
+
+    it 'add the users to the participants list' do
+      described_class.new(message: message).perform
+      expect(conversation.conversation_participants.map(&:user_id)).to match_array([first_agent.id, second_agent.id])
+    end
   end
 end
diff --git a/spec/services/messages/new_message_notification_service_spec.rb b/spec/services/messages/new_message_notification_service_spec.rb
index 72a71c853..bb35ec48a 100644
--- a/spec/services/messages/new_message_notification_service_spec.rb
+++ b/spec/services/messages/new_message_notification_service_spec.rb
@@ -13,13 +13,18 @@ describe Messages::NewMessageNotificationService do
     let(:account) { create(:account) }
     let(:assignee) { create(:user, account: account) }
     let(:participating_agent_1) { create(:user, account: account) }
+    let(:participating_agent_2) { create(:user, account: account) }
     let(:inbox) { create(:inbox, account: account) }
     let(:conversation) { create(:conversation, account: account, inbox: inbox, assignee: assignee) }
     let(:builder) { double }
 
     before do
       create(:inbox_member, inbox: inbox, user: participating_agent_1)
+      create(:inbox_member, inbox: inbox, user: participating_agent_2)
       create(:inbox_member, inbox: inbox, user: assignee)
+      create(:conversation_participant, conversation: conversation, user: participating_agent_1)
+      create(:conversation_participant, conversation: conversation, user: participating_agent_2)
+      create(:conversation_participant, conversation: conversation, user: assignee)
       allow(NotificationBuilder).to receive(:new).and_return(builder)
       allow(builder).to receive(:perform)
     end
@@ -31,12 +36,26 @@ describe Messages::NewMessageNotificationService do
         described_class.new(message: message).perform
       end
 
+      it 'creates notifications for other participating users' do
+        expect(NotificationBuilder).to have_received(:new).with(notification_type: 'participating_conversation_new_message',
+                                                                user: participating_agent_2,
+                                                                account: account,
+                                                                primary_actor: message)
+      end
+
       it 'creates notifications for assignee' do
         expect(NotificationBuilder).to have_received(:new).with(notification_type: 'assigned_conversation_new_message',
                                                                 user: assignee,
                                                                 account: account,
                                                                 primary_actor: message)
       end
+
+      it 'will not create notifications for the user who created the message' do
+        expect(NotificationBuilder).not_to have_received(:new).with(notification_type: 'participating_conversation_new_message',
+                                                                    user: participating_agent_1,
+                                                                    account: account,
+                                                                    primary_actor: message)
+      end
     end
 
     context 'when message is created by a contact' do
@@ -52,6 +71,34 @@ describe Messages::NewMessageNotificationService do
                                                                 account: account,
                                                                 primary_actor: message)
       end
+
+      it 'creates notifications for all participating users' do
+        expect(NotificationBuilder).to have_received(:new).with(notification_type: 'participating_conversation_new_message',
+                                                                user: participating_agent_1,
+                                                                account: account,
+                                                                primary_actor: message)
+        expect(NotificationBuilder).to have_received(:new).with(notification_type: 'participating_conversation_new_message',
+                                                                user: participating_agent_2,
+                                                                account: account,
+                                                                primary_actor: message)
+      end
+    end
+
+    context 'with multiple notifications are subscribed' do
+      let(:message) { create(:message, conversation: conversation, account: account) }
+
+      before do
+        assignee.notification_settings.find_by(account_id: account.id).update(selected_email_flags: %w[email_assigned_conversation_new_message
+                                                                                                       email_participating_conversation_new_message])
+        described_class.new(message: message).perform
+      end
+
+      it 'will not create assignee notifications for the assignee if participating notification was send' do
+        expect(NotificationBuilder).not_to have_received(:new).with(notification_type: 'assigned_conversation_new_message',
+                                                                    user: assignee,
+                                                                    account: account,
+                                                                    primary_actor: message)
+      end
     end
 
     context 'when message is created by assignee' do
@@ -62,6 +109,10 @@ describe Messages::NewMessageNotificationService do
       end
 
       it 'will not create notifications for the user who created the message' do
+        expect(NotificationBuilder).not_to have_received(:new).with(notification_type: 'participating_conversation_new_message',
+                                                                    user: assignee,
+                                                                    account: account,
+                                                                    primary_actor: message)
         expect(NotificationBuilder).not_to have_received(:new).with(notification_type: 'assigned_conversation_new_message',
                                                                     user: assignee,
                                                                     account: account,