diff --git a/app/assets/stylesheets/sections/issues.scss b/app/assets/stylesheets/sections/issues.scss
index 5a1b476fe25..ed7902fec3a 100644
--- a/app/assets/stylesheets/sections/issues.scss
+++ b/app/assets/stylesheets/sections/issues.scss
@@ -106,3 +106,7 @@ input.check_all_issues {
 #update_status {
   width: 100px;
 }
+
+.participants {
+  margin-bottom: 10px;
+}
diff --git a/app/helpers/projects_helper.rb b/app/helpers/projects_helper.rb
index 878b0913769..39290ec05bb 100644
--- a/app/helpers/projects_helper.rb
+++ b/app/helpers/projects_helper.rb
@@ -17,7 +17,7 @@ module ProjectsHelper
   end
 
   def link_to_member(project, author, opts = {})
-    default_opts = { avatar: true }
+    default_opts = { avatar: true, name: true, size: 16 }
     opts = default_opts.merge(opts)
 
     return "(deleted)" unless author
@@ -25,10 +25,10 @@ module ProjectsHelper
     author_html =  ""
 
     # Build avatar image tag
-    author_html << image_tag(gravatar_icon(author.try(:email)), width: 16, class: "avatar avatar-inline s16") if opts[:avatar]
+    author_html << image_tag(gravatar_icon(author.try(:email), opts[:size]), width: opts[:size], class: "avatar avatar-inline #{"s#{opts[:size]}" if opts[:size]}") if opts[:avatar]
 
     # Build name span tag
-    author_html << content_tag(:span, sanitize(author.name), class: 'author')
+    author_html << content_tag(:span, sanitize(author.name), class: 'author') if opts[:name]
 
     author_html = author_html.html_safe
 
diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index 11e3d8eed19..38440859064 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -6,6 +6,7 @@
 #
 module Issuable
   extend ActiveSupport::Concern
+  include Mentionable
 
   included do
     belongs_to :project
@@ -97,4 +98,18 @@ module Issuable
   def votes_count
     upvotes + downvotes
   end
+
+  # Return all users participating on the discussion
+  def participants
+    users = []
+    users << author
+    users << assignee if is_assigned?
+    mentions = []
+    mentions << self.mentioned_users
+    notes.each do |note|
+      users << note.author
+      mentions << note.mentioned_users
+    end
+    users.concat(mentions.reduce([], :|)).uniq
+  end
 end
diff --git a/app/models/concerns/mentionable.rb b/app/models/concerns/mentionable.rb
new file mode 100644
index 00000000000..f22070f8504
--- /dev/null
+++ b/app/models/concerns/mentionable.rb
@@ -0,0 +1,37 @@
+# == Mentionable concern
+#
+# Contains common functionality shared between Issues and Notes
+#
+# Used by Issue, Note
+#
+module Mentionable
+  extend ActiveSupport::Concern
+
+  def mentioned_users
+    users = []
+    return users if mentionable_text.blank?
+    has_project = self.respond_to? :project
+    matches = mentionable_text.scan(/@[a-zA-Z][a-zA-Z0-9_\-\.]*/)
+    matches.each do |match|
+      identifier = match.delete "@"
+      if has_project
+        id = project.users_projects.joins(:user).where(users: { username: identifier }).pluck(:user_id).first
+      else
+        id = User.where(username: identifier).pluck(:id).first
+      end
+      users << User.find(id) unless id.blank?
+    end
+    users.uniq
+  end
+
+  def mentionable_text
+    if self.class == Issue
+      description
+    elsif self.class == Note
+      note
+    else
+      nil
+    end
+  end
+
+end
diff --git a/app/models/note.rb b/app/models/note.rb
index 9a3481faaaa..56a8749e47d 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -19,6 +19,8 @@ require 'carrierwave/orm/activerecord'
 require 'file_size_validator'
 
 class Note < ActiveRecord::Base
+  include Mentionable
+
   attr_accessible :note, :noteable, :noteable_id, :noteable_type, :project_id,
                   :attachment, :line_code, :commit_id
 
diff --git a/app/services/notification_service.rb b/app/services/notification_service.rb
index 379d2c54629..b0243481b35 100644
--- a/app/services/notification_service.rb
+++ b/app/services/notification_service.rb
@@ -110,9 +110,11 @@ class NotificationService
     else
       opts.merge!(noteable_id: note.noteable_id)
       target = note.noteable
-      recipients = []
-      recipients << target.assignee if target.respond_to?(:assignee)
-      recipients << target.author if target.respond_to?(:author)
+      if target.respond_to?(:participants)
+        recipients = target.participants
+      else
+        recipients = []
+      end
     end
 
     # Get users who left comment in thread
@@ -181,7 +183,12 @@ class NotificationService
   end
 
   def new_resource_email(target, method)
-    recipients = reject_muted_users([target.assignee], target.project)
+    if target.respond_to?(:participants)
+      recipients = target.participants
+    else
+      recipients = []
+    end
+    recipients = reject_muted_users(recipients, target.project)
     recipients = recipients.concat(project_watchers(target.project)).uniq
     recipients.delete(target.author)
 
diff --git a/app/views/issues/show.html.haml b/app/views/issues/show.html.haml
index 2e204b8240d..891a01f14c9 100644
--- a/app/views/issues/show.html.haml
+++ b/app/views/issues/show.html.haml
@@ -65,4 +65,9 @@
     - else
       = link_to 'Close Issue', project_issue_path(@project, @issue, issue: {state_event: :close }, status_only: true), method: :put, class: "btn grouped close_issue", title: "Close Issue"
 
+.participants
+  %cite.cgray #{@issue.participants.count} participants
+  - @issue.participants.each do |participant|
+    = link_to_member(@project, participant, name: false, size: 24)
+
 .voting_notes#notes= render "notes/notes_with_form"
diff --git a/spec/services/notification_service_spec.rb b/spec/services/notification_service_spec.rb
index 21e4202f4ee..76501482303 100644
--- a/spec/services/notification_service_spec.rb
+++ b/spec/services/notification_service_spec.rb
@@ -19,7 +19,7 @@ describe NotificationService do
   describe 'Notes' do
     context 'issue note' do
       let(:issue) { create(:issue, assignee: create(:user)) }
-      let(:note) { create(:note_on_issue, noteable: issue, project_id: issue.project_id) }
+      let(:note) { create(:note_on_issue, noteable: issue, project_id: issue.project_id, note: '@mention referenced') }
 
       before do
         build_team(note.project)
@@ -30,6 +30,7 @@ describe NotificationService do
           should_email(@u_watcher.id)
           should_email(note.noteable.author_id)
           should_email(note.noteable.assignee_id)
+          should_email(@u_mentioned.id)
           should_not_email(note.author_id)
           should_not_email(@u_participating.id)
           should_not_email(@u_disabled.id)
@@ -235,9 +236,11 @@ describe NotificationService do
     @u_watcher = create(:user, notification_level: Notification::N_WATCH)
     @u_participating = create(:user, notification_level: Notification::N_PARTICIPATING)
     @u_disabled = create(:user, notification_level: Notification::N_DISABLED)
+    @u_mentioned = create(:user, username: 'mention', notification_level: Notification::N_WATCH)
 
     project.team << [@u_watcher, :master]
     project.team << [@u_participating, :master]
     project.team << [@u_disabled, :master]
+    project.team << [@u_mentioned, :master]
   end
 end