diff --git a/app/assets/javascripts/discourse/controllers/topic.js.es6 b/app/assets/javascripts/discourse/controllers/topic.js.es6
index 71be8528f2d..1071f6d7f7a 100644
--- a/app/assets/javascripts/discourse/controllers/topic.js.es6
+++ b/app/assets/javascripts/discourse/controllers/topic.js.es6
@@ -545,6 +545,14 @@ export default Ember.Controller.extend(SelectedPostsCount, BufferedContent, {
     changePostOwner(post) {
       this.get('selectedPosts').addObject(post);
       this.send('changeOwner');
+    },
+
+    convertToPublicTopic() {
+      this.get('content').convertTopic("public");
+    },
+
+    convertToPrivateMessage() {
+      this.get('content').convertTopic("private");
     }
   },
 
diff --git a/app/assets/javascripts/discourse/models/topic.js.es6 b/app/assets/javascripts/discourse/models/topic.js.es6
index 949386c9f2c..700e07aeb52 100644
--- a/app/assets/javascripts/discourse/models/topic.js.es6
+++ b/app/assets/javascripts/discourse/models/topic.js.es6
@@ -4,6 +4,7 @@ import { propertyEqual } from 'discourse/lib/computed';
 import { longDate } from 'discourse/lib/formatter';
 import computed from 'ember-addons/ember-computed-decorators';
 import ActionSummary from 'discourse/models/action-summary';
+import { popupAjaxError } from 'discourse/lib/ajax-error';
 
 export function loadTopicView(topic, args) {
   const topicId = topic.get('id');
@@ -446,8 +447,13 @@ const Topic = RestModel.extend({
     }).finally(()=>this.set('archiving', false));
 
     return promise;
-  }
+  },
 
+  convertTopic(type) {
+    return Discourse.ajax(`/t/${this.get('id')}/convert-topic/${type}`, {type: 'PUT'}).then(() => {
+      window.location.reload();
+    }).catch(popupAjaxError);
+  }
 });
 
 Topic.reopenClass({
diff --git a/app/assets/javascripts/discourse/templates/topic.hbs b/app/assets/javascripts/discourse/templates/topic.hbs
index 6772028a3f7..ace64e6e75a 100644
--- a/app/assets/javascripts/discourse/templates/topic.hbs
+++ b/app/assets/javascripts/discourse/templates/topic.hbs
@@ -256,6 +256,16 @@
       {{/if}}
     </li>
 
+    {{#if currentUser.admin}}
+      <li class="topic-admin-convert">
+        {{#if model.isPrivateMessage}}
+          {{d-button action="convertToPublicTopic" icon="comment" label="topic.actions.make_public"}}
+        {{else}}
+          {{d-button action="convertToPrivateMessage" icon="envelope" label="topic.actions.make_private"}}
+        {{/if}}
+      </li>
+    {{/if}}
+
     {{plugin-outlet "topic-admin-menu-buttons"}}
   {{/popup-menu}}
 {{/if}}
diff --git a/app/assets/javascripts/discourse/widgets/post-small-action.js.es6 b/app/assets/javascripts/discourse/widgets/post-small-action.js.es6
index 4940b6446a8..4f56c01ddb5 100644
--- a/app/assets/javascripts/discourse/widgets/post-small-action.js.es6
+++ b/app/assets/javascripts/discourse/widgets/post-small-action.js.es6
@@ -20,7 +20,9 @@ const icons = {
   'visible.disabled': 'eye-slash',
   'split_topic': 'sign-out',
   'invited_user': 'plus-circle',
-  'removed_user': 'minus-circle'
+  'removed_user': 'minus-circle',
+  'public_topic': 'comment',
+  'private_topic': 'envelope'
 };
 
 export default createWidget('post-small-action', {
diff --git a/app/controllers/topics_controller.rb b/app/controllers/topics_controller.rb
index 8e02fad1ee0..9a97662a656 100644
--- a/app/controllers/topics_controller.rb
+++ b/app/controllers/topics_controller.rb
@@ -27,6 +27,7 @@ class TopicsController < ApplicationController
                                           :change_timestamps,
                                           :archive_message,
                                           :move_to_inbox,
+                                          :convert_topic,
                                           :bookmark]
 
   before_filter :consider_user_for_promotion, only: :show
@@ -510,6 +511,22 @@ class TopicsController < ApplicationController
     render nothing: true
   end
 
+  def convert_topic
+    params.require(:id)
+    params.require(:type)
+    topic = Topic.find_by(id: params[:id])
+    guardian.ensure_can_convert_topic!(topic)
+
+    if params[:type] == "public"
+      converted_topic = topic.convert_to_public_topic(current_user)
+    else
+      converted_topic = topic.convert_to_private_message(current_user)
+    end
+    render_topic_changes(converted_topic)
+  rescue ActiveRecord::RecordInvalid => ex
+    render_json_error(ex)
+  end
+
   private
 
   def toggle_mute
diff --git a/app/models/topic.rb b/app/models/topic.rb
index 6d516e360c7..2fc44840516 100644
--- a/app/models/topic.rb
+++ b/app/models/topic.rb
@@ -1047,6 +1047,18 @@ SQL
     [result].flatten unless result.blank?
   end
 
+  def convert_to_public_topic(user)
+    public_topic = TopicConverter.new(self, user).convert_to_public_topic
+    add_small_action(user, "public_topic") if public_topic
+    public_topic
+  end
+
+  def convert_to_private_message(user)
+    private_topic = TopicConverter.new(self, user).convert_to_private_message
+    add_small_action(user, "private_topic") if private_topic
+    private_topic
+  end
+
   private
 
   def update_category_topic_count_by(num)
diff --git a/app/models/topic_converter.rb b/app/models/topic_converter.rb
new file mode 100644
index 00000000000..4e40c283424
--- /dev/null
+++ b/app/models/topic_converter.rb
@@ -0,0 +1,69 @@
+class TopicConverter
+
+  attr_reader :topic
+
+  def initialize(topic, user)
+    @topic = topic
+    @user = user
+  end
+
+  def convert_to_public_topic
+    Topic.transaction do
+      @topic.category_id = SiteSetting.allow_uncategorized_topics ? SiteSetting.uncategorized_category_id : Category.where(read_restricted: false).first.id
+      @topic.archetype = Archetype.default
+      @topic.save
+      update_user_stats
+      watch_topic(topic)
+    end
+    @topic
+  end
+
+  def convert_to_private_message
+    Topic.transaction do
+      @topic.category_id = nil
+      @topic.archetype = Archetype.private_message
+      add_allowed_users
+      @topic.save
+      watch_topic(topic)
+    end
+    @topic
+  end
+
+  private
+
+  def update_user_stats
+    @topic.posts.where(deleted_at: nil).each do |p|
+      user = User.find(p.user_id)
+      # update posts count
+      user.user_stat.post_count += 1
+      user.user_stat.save!
+    end
+    # update topics count
+    @topic.user.user_stat.topic_count += 1
+    @topic.user.user_stat.save!
+  end
+
+  def add_allowed_users
+    @topic.posts.where(deleted_at: nil).each do |p|
+      user = User.find(p.user_id)
+      @topic.topic_allowed_users.build(user_id: user.id) unless @topic.topic_allowed_users.where(user_id: user.id).exists?
+      # update posts count
+      user.user_stat.post_count -= 1
+      user.user_stat.save!
+    end
+    @topic.topic_allowed_users.build(user_id: @user.id)
+    # update topics count
+    @topic.user.user_stat.topic_count -= 1
+    @topic.user.user_stat.save!
+  end
+
+  def watch_topic(topic)
+    @topic.notifier.watch_topic!(topic.user_id)
+
+    @topic.topic_allowed_users(true).each do |tau|
+      next if tau.user_id == -1 || tau.user_id == topic.user_id
+      topic.notifier.watch!(tau.user_id)
+    end
+  end
+
+end
diff --git a/config/locales/client.en.yml b/config/locales/client.en.yml
index f5ce598f9af..c9d7675d983 100644
--- a/config/locales/client.en.yml
+++ b/config/locales/client.en.yml
@@ -121,6 +121,8 @@ en:
       email: 'send this link in an email'
 
     action_codes:
+      public_topic: "made this topic public %{when}"
+      private_topic: "made this topic private %{when}"
       split_topic: "split this topic %{when}"
       invited_user: "invited %{who} %{when}"
       removed_user: "removed %{who} %{when}"
@@ -1344,6 +1346,8 @@ en:
         invisible: "Make Unlisted"
         visible: "Make Listed"
         reset_read: "Reset Read Data"
+        make_public: "Make Public Topic"
+        make_private: "Make Private Message"
 
       feature:
         pin: "Pin Topic"
@@ -2983,4 +2987,3 @@ en:
           top: "There are no more top topics."
           bookmarks: "There are no more bookmarked topics."
           search: "There are no more search results."
-
diff --git a/config/routes.rb b/config/routes.rb
index a0c233965f0..31682f385ec 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -486,6 +486,7 @@ Discourse::Application.routes.draw do
   delete "t/:id" => "topics#destroy"
   put "t/:id/archive-message" => "topics#archive_message"
   put "t/:id/move-to-inbox" => "topics#move_to_inbox"
+  put "t/:id/convert-topic/:type" => "topics#convert_topic"
   put "topics/bulk"
   put "topics/reset-new" => 'topics#reset_new'
   post "topics/timings"
diff --git a/lib/guardian/topic_guardian.rb b/lib/guardian/topic_guardian.rb
index c6963214d3c..04c81a894af 100644
--- a/lib/guardian/topic_guardian.rb
+++ b/lib/guardian/topic_guardian.rb
@@ -58,6 +58,10 @@ module TopicGuardian
     !Discourse.static_doc_topic_ids.include?(topic.id)
   end
 
+  def can_convert_topic?(topic)
+    topic && !topic.trashed? && is_admin?
+  end
+
   def can_reply_as_new_topic?(topic)
     authenticated? && topic && not(topic.private_message?) && @user.has_trust_level?(TrustLevel[1])
   end
diff --git a/spec/components/guardian_spec.rb b/spec/components/guardian_spec.rb
index 5a6d9776fdf..969067404ef 100644
--- a/spec/components/guardian_spec.rb
+++ b/spec/components/guardian_spec.rb
@@ -872,6 +872,24 @@ describe Guardian do
 
   end
 
+  context 'can_convert_topic?' do
+    it 'returns false with a nil object' do
+      expect(Guardian.new(user).can_convert_topic?(nil)).to be_falsey
+    end
+
+    it 'returns false when not logged in' do
+      expect(Guardian.new.can_convert_topic?(topic)).to be_falsey
+    end
+
+    it 'returns false when not admin' do
+      expect(Guardian.new(moderator).can_convert_topic?(topic)).to be_falsey
+    end
+
+    it 'returns true when an admin' do
+      expect(Guardian.new(admin).can_convert_topic?(topic)).to be_truthy
+    end
+  end
+
   describe 'can_edit?' do
 
     it 'returns false with a nil object' do
diff --git a/spec/controllers/topics_controller_spec.rb b/spec/controllers/topics_controller_spec.rb
index 4a82c8074f9..780e6f4a487 100644
--- a/spec/controllers/topics_controller_spec.rb
+++ b/spec/controllers/topics_controller_spec.rb
@@ -1235,4 +1235,63 @@ describe TopicsController do
       expect(response.headers['X-Robots-Tag']).to eq(nil)
     end
   end
+
+  context "convert_topic" do
+    it 'needs you to be logged in' do
+      expect { xhr :put, :convert_topic, id: 111, type: "private" }.to raise_error(Discourse::NotLoggedIn)
+    end
+
+    describe 'converting public topic to private message' do
+      let(:user) { Fabricate(:user) }
+      let(:topic) { Fabricate(:topic, user: user) }
+
+      it "raises an error when the user doesn't have permission to convert topic" do
+        log_in
+        xhr :put, :convert_topic, id: topic.id, type: "private"
+        expect(response).to be_forbidden
+      end
+
+      context "success" do
+        before do
+          admin = log_in(:admin)
+          Topic.any_instance.expects(:convert_to_private_message).with(admin).returns(topic)
+          xhr :put, :convert_topic, id: topic.id, type: "private"
+        end
+
+        it "returns success" do
+          expect(response).to be_success
+          result = ::JSON.parse(response.body)
+          expect(result['success']).to eq(true)
+          expect(result['url']).to be_present
+        end
+      end
+    end
+
+    describe 'converting private message to public topic' do
+      let(:user) { Fabricate(:user) }
+      let(:topic) { Fabricate(:topic, user: user) }
+
+      it "raises an error when the user doesn't have permission to convert topic" do
+        log_in
+        xhr :put, :convert_topic, id: topic.id, type: "public"
+        expect(response).to be_forbidden
+      end
+
+      context "success" do
+        before do
+          admin = log_in(:admin)
+          Topic.any_instance.expects(:convert_to_public_topic).with(admin).returns(topic)
+          xhr :put, :convert_topic, id: topic.id, type: "public"
+        end
+
+        it "returns success" do
+          expect(response).to be_success
+          result = ::JSON.parse(response.body)
+          expect(result['success']).to eq(true)
+          expect(result['url']).to be_present
+        end
+      end
+    end
+  end
+
 end
diff --git a/spec/models/topic_converter_spec.rb b/spec/models/topic_converter_spec.rb
new file mode 100644
index 00000000000..96bd61e9153
--- /dev/null
+++ b/spec/models/topic_converter_spec.rb
@@ -0,0 +1,68 @@
+require 'rails_helper'
+
+describe TopicConverter do
+
+  context 'convert_to_public_topic' do
+    let(:admin) { Fabricate(:admin) }
+    let(:author) { Fabricate(:user) }
+    let(:private_message) { Fabricate(:private_message_topic, user: author) }
+
+    context 'success' do
+      it "converts private message to regular topic" do
+        topic = private_message.convert_to_public_topic(admin)
+        expect(topic).to be_valid
+        expect(topic.archetype).to eq("regular")
+      end
+
+      it "updates user stats" do
+        topic_user = TopicUser.create!(user_id: author.id, topic_id: private_message.id, posted: true)
+        expect(private_message.user.user_stat.topic_count).to eq(0)
+        private_message.convert_to_public_topic(admin)
+        expect(private_message.reload.user.user_stat.topic_count).to eq(1)
+        expect(topic_user.reload.notification_level).to eq(TopicUser.notification_levels[:watching])
+      end
+    end
+  end
+
+  context 'convert_to_private_message' do
+    let(:admin) { Fabricate(:admin) }
+    let(:author) { Fabricate(:user) }
+    let(:topic) { Fabricate(:topic, user: author) }
+
+    context 'success' do
+      it "converts regular topic to private message" do
+        private_message = topic.convert_to_private_message(admin)
+        expect(private_message).to be_valid
+        expect(topic.archetype).to eq("private_message")
+      end
+
+      it "updates user stats" do
+        Fabricate(:post, topic: topic, user: author)
+        topic_user = TopicUser.create!(user_id: author.id, topic_id: topic.id, posted: true)
+        author.user_stat.topic_count = 1
+        author.user_stat.save
+        expect(topic.user.user_stat.topic_count).to eq(1)
+        topic.convert_to_private_message(admin)
+
+        expect(topic.reload.topic_allowed_users.where(user_id: author.id).count).to eq(1)
+        expect(topic.reload.user.user_stat.topic_count).to eq(0)
+        expect(topic_user.reload.notification_level).to eq(TopicUser.notification_levels[:watching])
+      end
+    end
+
+    context 'topic has replies' do
+      before do
+        @replied_user = Fabricate(:coding_horror)
+        create_post(topic: topic, user: @replied_user)
+        topic.reload
+      end
+
+      it 'adds users who replied to topic in Private Message' do
+        topic.convert_to_private_message(admin)
+
+        expect(topic.reload.topic_allowed_users.where(user_id: @replied_user.id).count).to eq(1)
+        expect(topic.reload.user.user_stat.post_count).to eq(0)
+      end
+    end
+  end
+end