diff --git a/app/assets/javascripts/discourse/controllers/topic.js.es6 b/app/assets/javascripts/discourse/controllers/topic.js.es6
index 2e351654e9e..49110ce83bf 100644
--- a/app/assets/javascripts/discourse/controllers/topic.js.es6
+++ b/app/assets/javascripts/discourse/controllers/topic.js.es6
@@ -518,6 +518,14 @@ export default Ember.Controller.extend(BufferedContent, {
       this.send('changeOwner');
     },
 
+    lockPost(post) {
+      return post.updatePostField('locked', true);
+    },
+
+    unlockPost(post) {
+      return post.updatePostField('locked', false);
+    },
+
     grantBadge(post) {
       this.set("selectedPostIds", [post.id]);
       this.send('showGrantBadgeModal');
diff --git a/app/assets/javascripts/discourse/lib/transform-post.js.es6 b/app/assets/javascripts/discourse/lib/transform-post.js.es6
index ac81e64e682..03ac928c1fe 100644
--- a/app/assets/javascripts/discourse/lib/transform-post.js.es6
+++ b/app/assets/javascripts/discourse/lib/transform-post.js.es6
@@ -77,6 +77,7 @@ export function transformBasicPost(post) {
     cooked_hidden: !!post.cooked_hidden,
     expandablePost: false,
     replyCount: post.reply_count,
+    locked: post.locked
   };
 
   _additionalAttributes.forEach(a => postAtts[a] = post[a]);
diff --git a/app/assets/javascripts/discourse/templates/topic.hbs b/app/assets/javascripts/discourse/templates/topic.hbs
index b8ffe6b5e96..1c9678a69c1 100644
--- a/app/assets/javascripts/discourse/templates/topic.hbs
+++ b/app/assets/javascripts/discourse/templates/topic.hbs
@@ -175,6 +175,8 @@
                 rebakePost=(action "rebakePost")
                 changePostOwner=(action "changePostOwner")
                 grantBadge=(action "grantBadge")
+                lockPost=(action "lockPost")
+                unlockPost=(action "unlockPost")
                 unhidePost=(action "unhidePost")
                 replyToPost=(action "replyToPost")
                 toggleWiki=(action "toggleWiki")
diff --git a/app/assets/javascripts/discourse/widgets/post-admin-menu.js.es6 b/app/assets/javascripts/discourse/widgets/post-admin-menu.js.es6
index e21317a74fb..d79580ae45a 100644
--- a/app/assets/javascripts/discourse/widgets/post-admin-menu.js.es6
+++ b/app/assets/javascripts/discourse/widgets/post-admin-menu.js.es6
@@ -73,6 +73,15 @@ export function buildManageButtons(attrs, currentUser) {
       action: 'grantBadge',
       className: 'grant-badge'
     });
+
+    const action = attrs.locked ? "unlock" : "lock";
+    contents.push({
+      icon: action,
+      label: `post.controls.${action}_post`,
+      action: `${action}Post`,
+      title: `post.controls.${action}_post_description`,
+      className: `${action}-post`
+    });
   }
 
   if (attrs.canManage || attrs.canWiki) {
diff --git a/app/assets/javascripts/discourse/widgets/post.js.es6 b/app/assets/javascripts/discourse/widgets/post.js.es6
index 471ca682933..29618627e69 100644
--- a/app/assets/javascripts/discourse/widgets/post.js.es6
+++ b/app/assets/javascripts/discourse/widgets/post.js.es6
@@ -7,6 +7,7 @@ import { h } from 'virtual-dom';
 import DiscourseURL from 'discourse/lib/url';
 import { dateNode } from 'discourse/helpers/node';
 import { translateSize, avatarUrl, formatUsername } from 'discourse/lib/utilities';
+import hbs from 'discourse/widgets/hbs-compiler';
 
 export function avatarImg(wanted, attrs) {
   const size = translateSize(wanted);
@@ -139,6 +140,12 @@ createWidget('post-avatar', {
   }
 });
 
+createWidget('post-locked-indicator', {
+  tagName: 'div.post-info.post-locked',
+  template: hbs`{{d-icon "lock"}}`,
+  title: () => I18n.t("post.locked")
+});
+
 createWidget('post-email-indicator', {
   tagName: 'div.post-info.via-email',
 
@@ -207,6 +214,10 @@ createWidget('post-meta-data', {
       result.push(this.attach('post-email-indicator', attrs));
     }
 
+    if (attrs.locked) {
+      result.push(this.attach('post-locked-indicator', attrs));
+    }
+
     if (attrs.version > 1 || attrs.wiki) {
       result.push(this.attach('post-edits-indicator', attrs));
     }
diff --git a/app/assets/stylesheets/common/base/topic-post.scss b/app/assets/stylesheets/common/base/topic-post.scss
index bcf774d15a1..b10b4d18331 100644
--- a/app/assets/stylesheets/common/base/topic-post.scss
+++ b/app/assets/stylesheets/common/base/topic-post.scss
@@ -320,8 +320,11 @@ aside.quote {
 }
 
 .post-info {
+
   &.via-email, &.whisper {
     line-height: $line-height-medium;
+  }
+  &.via-email, &.whisper, &.post-locked {
     margin-right: 5px;
     .d-icon {
       font-size: $font-0;
diff --git a/app/controllers/posts_controller.rb b/app/controllers/posts_controller.rb
index a091e7e69d0..639ee168c29 100644
--- a/app/controllers/posts_controller.rb
+++ b/app/controllers/posts_controller.rb
@@ -4,12 +4,34 @@ require_dependency 'post_destroyer'
 require_dependency 'post_merger'
 require_dependency 'distributed_memoizer'
 require_dependency 'new_post_result_serializer'
+require_dependency 'post_locker'
 
 class PostsController < ApplicationController
 
-  before_action :ensure_logged_in, except: [:show, :replies, :by_number, :short_link, :reply_history, :replyIids, :revisions, :latest_revision, :expand_embed, :markdown_id, :markdown_num, :cooked, :latest, :user_posts_feed]
+  before_action :ensure_logged_in, except: [
+    :show,
+    :replies,
+    :by_number,
+    :short_link,
+    :reply_history,
+    :replyIids,
+    :revisions,
+    :latest_revision,
+    :expand_embed,
+    :markdown_id,
+    :markdown_num,
+    :cooked,
+    :latest,
+    :user_posts_feed
+  ]
 
-  skip_before_action :preload_json, :check_xhr, only: [:markdown_id, :markdown_num, :short_link, :latest, :user_posts_feed]
+  skip_before_action :preload_json, :check_xhr, only: [
+    :markdown_id,
+    :markdown_num,
+    :short_link,
+    :latest,
+    :user_posts_feed
+  ]
 
   def markdown_id
     markdown Post.find(params[:id].to_i)
@@ -381,6 +403,13 @@ class PostsController < ApplicationController
     render_json_dump(result)
   end
 
+  def locked
+    post = find_post_from_params
+    locker = PostLocker.new(post, current_user)
+    params[:locked] === "true" ? locker.lock : locker.unlock
+    render_json_dump(locked: post.locked?)
+  end
+
   def bookmark
     if params[:bookmarked] == "true"
       post = find_post_from_params
diff --git a/app/models/post.rb b/app/models/post.rb
index 855d770349c..7a8ce9a5731 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -735,6 +735,10 @@ class Post < ActiveRecord::Base
     UserActionCreator.log_post(self)
   end
 
+  def locked?
+    locked_by_id.present?
+  end
+
   private
 
   def parse_quote_into_arguments(quote)
diff --git a/app/models/user_history.rb b/app/models/user_history.rb
index d2f7f25a947..980ba8728f0 100644
--- a/app/models/user_history.rb
+++ b/app/models/user_history.rb
@@ -63,7 +63,9 @@ class UserHistory < ActiveRecord::Base
                           backup_download: 45,
                           backup_destroy: 46,
                           notified_about_get_a_room: 47,
-                          change_name: 48)
+                          change_name: 48,
+                          post_locked: 49,
+                          post_unlocked: 50)
   end
 
   # Staff actions is a subset of all actions, used to audit actions taken by staff users.
@@ -104,7 +106,9 @@ class UserHistory < ActiveRecord::Base
                         :activate_user,
                         :change_readonly_mode,
                         :backup_download,
-                        :backup_destroy]
+                        :backup_destroy,
+                        :post_locked,
+                        :post_unlocked]
   end
 
   def self.staff_action_ids
diff --git a/app/serializers/post_serializer.rb b/app/serializers/post_serializer.rb
index d756ee1dd31..3f1b2a7254d 100644
--- a/app/serializers/post_serializer.rb
+++ b/app/serializers/post_serializer.rb
@@ -69,7 +69,8 @@ class PostSerializer < BasicPostSerializer
              :is_auto_generated,
              :action_code,
              :action_code_who,
-             :last_wiki_edit
+             :last_wiki_edit,
+             :locked
 
   def initialize(object, opts)
     super(object, opts)
@@ -354,6 +355,15 @@ class PostSerializer < BasicPostSerializer
     include_action_code? && action_code_who.present?
   end
 
+  def locked
+    true
+  end
+
+  # Only show locked posts to the users who made the post and staff
+  def include_locked?
+    object.locked? && (yours || scope.is_staff?)
+  end
+
   def last_wiki_edit
     object.revisions.last.updated_at
   end
diff --git a/app/services/staff_action_logger.rb b/app/services/staff_action_logger.rb
index eb5d87abf14..6f57021af12 100644
--- a/app/services/staff_action_logger.rb
+++ b/app/services/staff_action_logger.rb
@@ -95,6 +95,14 @@ class StaffActionLogger
                                            target_user_id: user.id))
   end
 
+  def log_post_lock(post, opts = {})
+    raise Discourse::InvalidParameters.new(:post) unless post && post.is_a?(Post)
+    UserHistory.create!(params(opts).merge(
+      action: UserHistory.actions[opts[:locked] ? :post_locked : :post_unlocked],
+      post_id: post.id)
+    )
+  end
+
   def log_site_setting_change(setting_name, previous_value, new_value, opts = {})
     raise Discourse::InvalidParameters.new(:setting_name) unless setting_name.present? && SiteSetting.respond_to?(setting_name)
     UserHistory.create(params(opts).merge(action: UserHistory.actions[:change_site_setting],
diff --git a/config/locales/client.en.yml b/config/locales/client.en.yml
index 69184d393fc..dc948cbbdb6 100644
--- a/config/locales/client.en.yml
+++ b/config/locales/client.en.yml
@@ -1900,6 +1900,7 @@ en:
         other: "(post withdrawn by author, will be automatically deleted in %{count} hours unless flagged)"
       collapse: "collapse"
       expand_collapse: "expand/collapse"
+      locked: "a staff member has locked this post from being edited"
       gap:
         one: "view 1 hidden reply"
         other: "view {{count}} hidden replies"
@@ -1981,6 +1982,10 @@ en:
         unhide: "Unhide"
         change_owner: "Change Ownership"
         grant_badge: "Grant Badge"
+        lock_post: "Lock Post"
+        lock_post_description: "prevent the poster from editing this post"
+        unlock_post: "Unlock Post"
+        unlock_post_description: "allow the poster to edit this post"
 
       actions:
         flag: 'Flag'
@@ -3220,6 +3225,8 @@ en:
             backup_destroy: "destroy backup"
             reviewed_post: "reviewed post"
             custom_staff: "plugin custom action"
+            post_locked: "post locked"
+            post_unlocked: "post unlocked"
         screened_emails:
           title: "Screened Emails"
           description: "When someone tries to create a new account, the following email addresses will be checked and the registration will be blocked, or some other action performed."
diff --git a/config/routes.rb b/config/routes.rb
index f3cb50b6fbf..23d6447d866 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -475,6 +475,7 @@ Discourse::Application.routes.draw do
     put "post_type"
     put "rebake"
     put "unhide"
+    put "locked"
     get "replies"
     get "revisions/latest" => "posts#latest_revision"
     get "revisions/:revision" => "posts#revisions", constraints: { revision: /\d+/ }
diff --git a/db/migrate/20180125185717_add_locked_by_to_posts.rb b/db/migrate/20180125185717_add_locked_by_to_posts.rb
new file mode 100644
index 00000000000..ec832cdd94c
--- /dev/null
+++ b/db/migrate/20180125185717_add_locked_by_to_posts.rb
@@ -0,0 +1,5 @@
+class AddLockedByToPosts < ActiveRecord::Migration[5.1]
+  def change
+    add_column :posts, :locked_by_id, :integer
+  end
+end
diff --git a/lib/guardian/post_guardian.rb b/lib/guardian/post_guardian.rb
index bda12b7d947..da7411d1eb2 100644
--- a/lib/guardian/post_guardian.rb
+++ b/lib/guardian/post_guardian.rb
@@ -46,6 +46,10 @@ module PostGuardian
     !!result
   end
 
+  def can_lock_post?(post)
+    can_see_post?(post) && is_staff?
+  end
+
   def can_defer_flags?(post)
     can_see_post?(post) && is_staff? && post
   end
@@ -98,6 +102,9 @@ module PostGuardian
 
     return true if is_admin?
 
+    # Must be staff to edit a locked post
+    return false if post.locked? && !is_staff?
+
     if is_staff? || @user.has_trust_level?(TrustLevel[4])
       return can_create_post?(post.topic)
     end
@@ -106,6 +113,7 @@ module PostGuardian
       return false
     end
 
+
     if post.wiki && (@user.trust_level >= SiteSetting.min_trust_to_edit_wiki_post.to_i)
       return can_create_post?(post.topic)
     end
@@ -114,6 +122,7 @@ module PostGuardian
       return false
     end
 
+
     if is_my_own?(post)
       if post.hidden?
         return false if post.hidden_at.present? &&
diff --git a/lib/post_locker.rb b/lib/post_locker.rb
new file mode 100644
index 00000000000..d78951231c4
--- /dev/null
+++ b/lib/post_locker.rb
@@ -0,0 +1,23 @@
+class PostLocker
+  def initialize(post, user)
+    @post, @user = post, user
+  end
+
+  def lock
+    Guardian.new(@user).ensure_can_lock_post!(@post)
+
+    Post.transaction do
+      @post.update_column(:locked_by_id, @user.id)
+      StaffActionLogger.new(@user).log_post_lock(@post, locked: true)
+    end
+  end
+
+  def unlock
+    Guardian.new(@user).ensure_can_lock_post!(@post)
+
+    Post.transaction do
+      @post.update_column(:locked_by_id, nil)
+      StaffActionLogger.new(@user).log_post_lock(@post, locked: false)
+    end
+  end
+end
diff --git a/spec/components/guardian_spec.rb b/spec/components/guardian_spec.rb
index a849e68cb22..09d4dc042d4 100644
--- a/spec/components/guardian_spec.rb
+++ b/spec/components/guardian_spec.rb
@@ -2,6 +2,7 @@ require 'rails_helper';
 
 require 'guardian'
 require_dependency 'post_destroyer'
+require_dependency 'post_locker'
 
 describe Guardian do
 
@@ -1091,6 +1092,11 @@ describe Guardian do
         expect(Guardian.new(post.user).can_edit?(post)).to be_truthy
       end
 
+      it 'returns false if you try to edit a locked post' do
+        post.locked_by_id = moderator.id
+        expect(Guardian.new(post.user).can_edit?(post)).to be_falsey
+      end
+
       it "returns false if the post is hidden due to flagging and it's too soon" do
         post.hidden = true
         post.hidden_at = Time.now
@@ -1164,6 +1170,11 @@ describe Guardian do
         expect(Guardian.new(moderator).can_edit?(post)).to be_truthy
       end
 
+      it 'returns true as a moderator, even if locked' do
+        post.locked_by_id = admin.id
+        expect(Guardian.new(moderator).can_edit?(post)).to be_truthy
+      end
+
       it 'returns true as an admin' do
         expect(Guardian.new(admin).can_edit?(post)).to be_truthy
       end
diff --git a/spec/components/post_locker_spec.rb b/spec/components/post_locker_spec.rb
new file mode 100644
index 00000000000..dd1e0291a04
--- /dev/null
+++ b/spec/components/post_locker_spec.rb
@@ -0,0 +1,49 @@
+require 'rails_helper'
+require_dependency 'post_locker'
+
+describe PostLocker do
+  let(:moderator) { Fabricate(:moderator) }
+  let(:post) { Fabricate(:post) }
+
+  it "doesn't allow regular users to lock posts" do
+    expect {
+      PostLocker.new(post, post.user).lock
+    }.to raise_error(Discourse::InvalidAccess)
+
+    expect(post).not_to be_locked
+    expect(post.locked_by_id).to be_blank
+  end
+
+  it "doesn't allow regular users to unlock posts" do
+    PostLocker.new(post, moderator).lock
+
+    expect {
+      PostLocker.new(post, post.user).lock
+    }.to raise_error(Discourse::InvalidAccess)
+
+    expect(post).to be_locked
+    expect(post.locked_by_id).to eq(moderator.id)
+  end
+
+  it "allows staff to lock and unlock posts" do
+    expect(post).not_to be_locked
+    expect(post.locked_by_id).to be_blank
+
+    PostLocker.new(post, moderator).lock
+    expect(post).to be_locked
+    expect(post.locked_by_id).to eq(moderator.id)
+    expect(UserHistory.where(
+      acting_user_id: moderator.id,
+      action: UserHistory.actions[:post_locked]
+    ).exists?).to eq(true)
+
+    PostLocker.new(post, moderator).unlock
+    expect(post).not_to be_locked
+    expect(post.locked_by_id).to be_blank
+    expect(UserHistory.where(
+      acting_user_id: moderator.id,
+      action: UserHistory.actions[:post_unlocked]
+    ).exists?).to eq(true)
+  end
+
+end
diff --git a/spec/requests/posts_controller_spec.rb b/spec/requests/posts_controller_spec.rb
index 62256403bf0..6d290d0e1aa 100644
--- a/spec/requests/posts_controller_spec.rb
+++ b/spec/requests/posts_controller_spec.rb
@@ -199,4 +199,23 @@ RSpec.describe PostsController do
       end
     end
   end
+
+  describe "#locked" do
+    before do
+      sign_in(Fabricate(:moderator))
+    end
+
+    it 'can lock and unlock the post' do
+      put "/posts/#{public_post.id}/locked.json", params: { locked: "true" }
+      expect(response).to be_success
+      public_post.reload
+      expect(public_post).to be_locked
+
+      put "/posts/#{public_post.id}/locked.json", params: { locked: "false" }
+      expect(response).to be_success
+      public_post.reload
+      expect(public_post).not_to be_locked
+    end
+  end
+
 end