diff --git a/CHANGELOG b/CHANGELOG
index b6c39ae5f71f49eb668e4915d85108e3aa019548..0897a712eaf3f63b684f96fca7e9ab1d1facf577 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,7 @@
 Please view this file on the master branch, on stable branches it's out of date.
 
 v 7.10.0 (unreleased)
+  - Fix cross references when usernames, milestones, or project names contain underscores (Stan Hu)
   - enable line wrapping per default and remove the checkbox to toggle it (Hannes Rosenögger)
   - extend the commit calendar to show the actual commits made on a date (Hannes Rosenögger)
   - Add a service to support external wikis (Hannes Rosenögger)
diff --git a/app/models/note.rb b/app/models/note.rb
index 649e9b4e852e480bf47fbe170e393e2062bfee8d..27b583a869abd25ea2cbc110f792a74a0123ad1c 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -59,7 +59,7 @@ class Note < ActiveRecord::Base
 
   class << self
     def create_status_change_note(noteable, project, author, status, source)
-      body = "_Status changed to #{status}#{' by ' + source.gfm_reference if source}_"
+      body = "Status changed to #{status}#{' by ' + source.gfm_reference if source}"
 
       create(
         noteable: noteable,
@@ -95,9 +95,9 @@ class Note < ActiveRecord::Base
 
     def create_milestone_change_note(noteable, project, author, milestone)
       body = if milestone.nil?
-               '_Milestone removed_'
+               'Milestone removed'
              else
-               "_Milestone changed to #{milestone.title}_"
+               "Milestone changed to #{milestone.title}"
              end
 
       create(
@@ -110,7 +110,7 @@ class Note < ActiveRecord::Base
     end
 
     def create_assignee_change_note(noteable, project, author, assignee)
-      body = assignee.nil? ? '_Assignee removed_' : "_Reassigned to @#{assignee.username}_"
+      body = assignee.nil? ? 'Assignee removed' : "Reassigned to @#{assignee.username}"
 
       create({
         noteable: noteable,
@@ -140,7 +140,7 @@ class Note < ActiveRecord::Base
       end
 
       message << ' ' << 'label'.pluralize(labels_count)
-      body = "_#{message.capitalize}_"
+      body = "#{message.capitalize}"
 
       create(
         noteable: noteable,
@@ -170,14 +170,14 @@ class Note < ActiveRecord::Base
 
         commits_text = ActionController::Base.helpers.pluralize(existing_commits.length, 'commit')
 
-        branch = 
+        branch =
           if merge_request.for_fork?
             "#{merge_request.target_project_namespace}:#{merge_request.target_branch}"
           else
             merge_request.target_branch
           end
 
-        message = "* #{commit_ids} - _#{commits_text} from branch `#{branch}`_"
+        message = "* #{commit_ids} - #{commits_text} from branch `#{branch}`"
         body << message
         body << "\n"
       end
@@ -240,7 +240,7 @@ class Note < ActiveRecord::Base
                 where(noteable_id: noteable.id)
               end
 
-      notes.where('note like ?', cross_reference_note_content(gfm_reference)).
+      notes.where('note like ?', cross_reference_note_pattern(gfm_reference)).
         system.any?
     end
 
@@ -249,13 +249,18 @@ class Note < ActiveRecord::Base
     end
 
     def cross_reference_note_prefix
-      '_mentioned in '
+      'mentioned in '
     end
 
     private
 
     def cross_reference_note_content(gfm_reference)
-      cross_reference_note_prefix + "#{gfm_reference}_"
+      cross_reference_note_prefix + "#{gfm_reference}"
+    end
+
+    def cross_reference_note_pattern(gfm_reference)
+      # Older cross reference notes contained underscores for emphasis
+      "%" + cross_reference_note_content(gfm_reference) + "%"
     end
 
     # Prepend the mentioner's namespaced project path to the GFM reference for
diff --git a/app/services/notification_service.rb b/app/services/notification_service.rb
index 848ed77ebf8373f2e4e948de477f8b927f8d1cb4..cc5853144c56ef21d9e7f3b4660dc9e237b454ef 100644
--- a/app/services/notification_service.rb
+++ b/app/services/notification_service.rb
@@ -120,7 +120,7 @@ class NotificationService
     return true unless note.noteable_type.present?
 
     # ignore gitlab service messages
-    return true if note.note.start_with?('_Status changed to closed_')
+    return true if note.note.start_with?('Status changed to closed')
     return true if note.cross_reference? && note.system == true
 
     opts = { noteable_type: note.noteable_type, project_id: note.project_id }
diff --git a/doc/api/merge_requests.md b/doc/api/merge_requests.md
index 1f3fd26a241644d09cd7ecc2880ba94732a98afc..6a272539e45fb7db43877b74652fe24dbffcb0ed 100644
--- a/doc/api/merge_requests.md
+++ b/doc/api/merge_requests.md
@@ -375,7 +375,7 @@ Parameters:
     }
   },
   {
-    "note": "_Status changed to closed_",
+    "note": "Status changed to closed",
     "author": {
       "id": 11,
       "username": "admin",
diff --git a/doc/api/notes.md b/doc/api/notes.md
index c22e493562ab1f0b8df4fbca94582ec3f73419fa..ee2f9fa0eac7192ebe6f8d7b4fa7cc46d039d254 100644
--- a/doc/api/notes.md
+++ b/doc/api/notes.md
@@ -21,7 +21,7 @@ Parameters:
 [
   {
     "id": 302,
-    "body": "_Status changed to closed_",
+    "body": "Status changed to closed",
     "attachment": null,
     "author": {
       "id": 1,
diff --git a/spec/lib/gitlab/reference_extractor_spec.rb b/spec/lib/gitlab/reference_extractor_spec.rb
index 034f8ee7c45f599c441e0071f81579e8e732e05f..5ebe44f6fb79297f903c7e492819883ddf3567f4 100644
--- a/spec/lib/gitlab/reference_extractor_spec.rb
+++ b/spec/lib/gitlab/reference_extractor_spec.rb
@@ -120,4 +120,18 @@ describe Gitlab::ReferenceExtractor do
       expect(extracted[0][1].message).to eq(commit.message)
     end
   end
+
+  context 'with a project with an underscore' do
+    let(:project) { create(:project, path: 'test_project') }
+    let(:issue) { create(:issue, project: project) }
+
+    it 'handles project issue references' do
+      subject.analyze("this refers issue #{project.path_with_namespace}##{issue.iid}",
+          project)
+      extracted = subject.issues_for(project)
+      expect(extracted.size).to eq(1)
+      expect(extracted).to eq([issue])
+    end
+
+  end
 end
diff --git a/spec/models/note_spec.rb b/spec/models/note_spec.rb
index 17cb439c90e9850d8f40bf71ebcf15554116ee7c..a7bf5081d5b8a9c98176301132c712ab8e5823de 100644
--- a/spec/models/note_spec.rb
+++ b/spec/models/note_spec.rb
@@ -182,14 +182,14 @@ describe Note do
 
     describe '#note' do
       subject { super().note }
-      it { is_expected.to match(/Status changed to #{status}/) }
+      it { is_expected.to eq("Status changed to #{status}") }
     end
 
     it 'appends a back-reference if a closing mentionable is supplied' do
       commit = double('commit', gfm_reference: 'commit 123456')
       n = Note.create_status_change_note(thing, project, author, status, commit)
 
-      expect(n.note).to match(/Status changed to #{status} by commit 123456/)
+      expect(n.note).to eq("Status changed to #{status} by commit 123456")
     end
   end
 
@@ -197,7 +197,7 @@ describe Note do
     let(:project) { create(:project) }
     let(:thing) { create(:issue, project: project) }
     let(:author) { create(:user) }
-    let(:assignee) { create(:user) }
+    let(:assignee) { create(:user, username: "assigned_user") }
 
     subject { Note.create_assignee_change_note(thing, project, author, assignee) }
 
@@ -227,7 +227,7 @@ describe Note do
 
     describe '#note' do
       subject { super().note }
-      it { is_expected.to match(/Reassigned to @#{assignee.username}/) }
+      it { is_expected.to eq('Reassigned to @assigned_user') }
     end
 
     context 'assignee is removed' do
@@ -235,11 +235,95 @@ describe Note do
 
       describe '#note' do
         subject { super().note }
-        it { is_expected.to match(/Assignee removed/) }
+        it { is_expected.to eq('Assignee removed') }
       end
     end
   end
 
+  describe '#create_labels_change_note' do
+    let(:project) { create(:project) }
+    let(:thing) { create(:issue, project: project) }
+    let(:author) { create(:user) }
+    let(:label1) { create(:label) }
+    let(:label2) { create(:label) }
+    let(:added_labels) { [label1, label2] }
+    let(:removed_labels) { [] }
+
+    subject { Note.create_labels_change_note(thing, project, author, added_labels, removed_labels) }
+
+    context 'creates and saves a Note' do
+      it { is_expected.to be_a Note }
+
+      describe '#id' do
+        subject { super().id }
+        it { is_expected.not_to be_nil }
+      end
+    end
+
+    describe '#noteable' do
+      subject { super().noteable }
+      it { is_expected.to eq(thing) }
+    end
+
+    describe '#project' do
+      subject { super().project }
+      it { is_expected.to eq(thing.project) }
+    end
+
+    describe '#author' do
+      subject { super().author }
+      it { is_expected.to eq(author) }
+    end
+
+    describe '#note' do
+      subject { super().note }
+      it { is_expected.to eq("Added ~#{label1.id} ~#{label2.id} labels") }
+    end
+
+    context 'label is removed' do
+      let(:added_labels) { [label1]  }
+      let(:removed_labels) { [label2] }
+
+      describe '#note' do
+        subject { super().note }
+        it { is_expected.to eq("Added ~#{label1.id} and removed ~#{label2.id} labels") }
+      end
+    end
+  end
+
+  describe '#create_milestone_change_note' do
+    let(:project) { create(:project) }
+    let(:thing) { create(:issue, project: project) }
+    let(:milestone) { create(:milestone, project: project, title: "first_milestone") }
+    let(:author) { create(:user) }
+
+    subject { Note.create_milestone_change_note(thing, project, author, milestone) }
+
+    context 'creates and saves a Note' do
+      it { is_expected.to be_a Note }
+
+      describe '#id' do
+        subject { super().id }
+        it { is_expected.not_to be_nil }
+      end
+    end
+
+    describe '#project' do
+      subject { super().project }
+      it { is_expected.to eq(thing.project) }
+    end
+
+    describe '#author' do
+      subject { super().author }
+      it { is_expected.to eq(author) }
+    end
+
+    describe '#note' do
+      subject { super().note }
+      it { is_expected.to eq("Milestone changed to first_milestone") }
+    end
+  end
+
   describe '#create_cross_reference_note' do
     let(:project)    { create(:project) }
     let(:author)     { create(:user) }
@@ -272,7 +356,7 @@ describe Note do
 
       describe '#note' do
         subject { super().note }
-        it { is_expected.to eq("_mentioned in merge request !#{mergereq.iid}_") }
+        it { is_expected.to eq("mentioned in merge request !#{mergereq.iid}") }
       end
     end
 
@@ -288,7 +372,7 @@ describe Note do
 
       describe '#note' do
         subject { super().note }
-        it { is_expected.to eq("_mentioned in commit #{commit.sha}_") }
+        it { is_expected.to eq("mentioned in commit #{commit.sha}") }
       end
     end
 
@@ -309,7 +393,7 @@ describe Note do
 
       describe '#note' do
         subject { super().note }
-        it { is_expected.to eq("_mentioned in issue ##{issue.iid}_") }
+        it { is_expected.to eq("mentioned in issue ##{issue.iid}") }
       end
     end
 
@@ -330,7 +414,7 @@ describe Note do
 
       describe '#note' do
         subject { super().note }
-        it { is_expected.to eq("_mentioned in merge request !#{mergereq.iid}_") }
+        it { is_expected.to eq("mentioned in merge request !#{mergereq.iid}") }
       end
     end
 
@@ -362,7 +446,7 @@ describe Note do
 
       describe '#note' do
         subject { super().note }
-        it { is_expected.to eq("_mentioned in issue ##{issue.iid}_") }
+        it { is_expected.to eq("mentioned in issue ##{issue.iid}") }
       end
     end
 
@@ -389,7 +473,7 @@ describe Note do
 
       describe '#note' do
         subject { super().note }
-        it { is_expected.to eq("_mentioned in commit #{parent_commit.id}_") }
+        it { is_expected.to eq("mentioned in commit #{parent_commit.id}") }
       end
     end
   end
@@ -421,6 +505,41 @@ describe Note do
       it { expect(Note.cross_reference_exists?(commit0, commit1)).to be_truthy }
       it { expect(Note.cross_reference_exists?(commit1, commit0)).to be_falsey }
     end
+
+    context 'legacy note with Markdown emphasis' do
+      let(:issue2) { create :issue, project: project }
+      let!(:note) do
+        create :note, system: true, noteable_id: issue2.id,
+                      noteable_type: "Issue", note: "_mentioned in issue " \
+                      "#{issue.project.path_with_namespace}##{issue.iid}_"
+      end
+
+      it 'detects if a mentionable with emphasis has been mentioned' do
+        expect(Note.cross_reference_exists?(issue2, issue)).to be_truthy
+      end
+    end
+  end
+
+  describe '#cross_references_with_underscores?' do
+    let(:project) { create :project, path: "first_project" }
+    let(:second_project) { create :project, path: "second_project" }
+
+    let(:author) { create :user }
+    let(:issue0) { create :issue, project: project }
+    let(:issue1) { create :issue, project: second_project }
+    let!(:note) { Note.create_cross_reference_note(issue0, issue1, author, project) }
+
+    it 'detects if a mentionable has already been mentioned' do
+      expect(Note.cross_reference_exists?(issue0, issue1)).to be_truthy
+    end
+
+    it 'detects if a mentionable has not already been mentioned' do
+      expect(Note.cross_reference_exists?(issue1, issue0)).to be_falsey
+    end
+
+    it 'detects that text has underscores' do
+      expect(note.note).to eq("mentioned in issue #{second_project.path_with_namespace}##{issue1.iid}")
+    end
   end
 
   describe '#system?' do
@@ -429,6 +548,8 @@ describe Note do
     let(:other)   { create(:issue, project: project) }
     let(:author)  { create(:user) }
     let(:assignee) { create(:user) }
+    let(:label) { create(:label) }
+    let(:milestone) { create(:milestone) }
 
     it 'should recognize user-supplied notes as non-system' do
       @note = create(:note_on_issue)
@@ -449,6 +570,16 @@ describe Note do
       @note = Note.create_assignee_change_note(issue, project, author, assignee)
       expect(@note).to be_system
     end
+
+    it 'should identify label-change notes as system notes' do
+      @note = Note.create_labels_change_note(issue, project, author, [label], [])
+      expect(@note).to be_system
+    end
+
+    it 'should identify milestone-change notes as system notes' do
+      @note = Note.create_milestone_change_note(issue, project, author, milestone)
+      expect(@note).to be_system
+    end
   end
 
   describe :authorization do