diff --git a/app/services/concerns/talk_service.rb b/app/services/concerns/talk_service.rb
index 0f2915ad..7ef675a3 100644
--- a/app/services/concerns/talk_service.rb
+++ b/app/services/concerns/talk_service.rb
@@ -101,15 +101,7 @@ def permitted_params
   end
 
   def rooted_params
-    # Parameters in Rails 5+ behave differently, because they no longer inherit from HashWithIndifferentAccess
-    # methods like slice will behave differently in Rails 4 than Rails 5
-    # In Rails 5, we will need to first to apply to_h and then slice.
-    # TODO: Can Remove version comparison once Prod is on Rails 5+
-    if Rails.version.starts_with?('4.2')
-      permitted_params.slice model_class.table_name
-    else
-      permitted_params.to_h.slice model_class.table_name
-    end
+    permitted_params.to_h.slice model_class.table_name
   end
 
   def unrooted_params
diff --git a/spec/controllers/users_controller_spec.rb b/spec/controllers/users_controller_spec.rb
index 11620dbf..b971f203 100644
--- a/spec/controllers/users_controller_spec.rb
+++ b/spec/controllers/users_controller_spec.rb
@@ -49,12 +49,7 @@
       it{ is_expected.to be_successful }
 
       it 'should return the usernames' do
-        # TODO: Remove version check once on Rails 5
-        # In Rails versions < 5, PG results when casted to_a,
-        # numeric types will get converted to string.
-        # After Rails 5, there is no typecasting, unless stated.
-        # See https://github.com/rails/rails/commit/c51f9b61ce1e167f5f58f07441adcfa117694301
-        expected_user_id = Rails.version.starts_with?('5') ? user.id : user.id.to_s
+        expected_user_id = user.id
         expect(response.json[:usernames]).to match_array [{
           'id' => expected_user_id,
           'login' => user.login,
diff --git a/spec/mailers/notification_mailer_spec.rb b/spec/mailers/notification_mailer_spec.rb
index 3fbefbef..0a83cbc6 100644
--- a/spec/mailers/notification_mailer_spec.rb
+++ b/spec/mailers/notification_mailer_spec.rb
@@ -99,34 +99,24 @@
     before(:each){ mailer.instance_variable_set :@user, user1 }
     let(:categories){ mailer.find_categories_for SubscriptionPreference.email_digests[frequency] }
 
-    # TODO: Once on Rails 5, Can Remove Version Check.
-    # Rails 5 introduces a change to ActiveRecord:Enum where it typecasts enum attributes to its string value.
-    # See: https://github.com/rails/rails/commit/c51f9b61ce1e167f5f58f07441adcfa117694301
-    # Luckily we can still send int values when doing a where clause on categories AND by Rails 5, we can also do a string array search of categories. So we do not need to update `find_notifications_for`
-    # Regardless, we will test thoroughly in Staging Canary When Up.
-    # Version Checks are on L112, L120, L128
-
     context 'with immediate' do
       let(:frequency){ :immediate }
       subject{ categories }
-      # TODO: When on Rails 5, Remove Version Checks (See L102 For Details)
-      expected_categories =  Rails.version.starts_with?('4.2') ? Subscription.categories.values_at(:mentions, :group_mentions, :system, :moderation_reports) : ['mentions', 'group_mentions', 'system', 'moderation_reports']
+      expected_categories =  ['mentions', 'group_mentions', 'system', 'moderation_reports']
       it{ is_expected.to match_array expected_categories }
     end
 
     context 'with daily' do
       let(:frequency){ :daily }
       subject{ categories }
-      # TODO: When on Rails 5, Remove Version Checks(See L102 For Details)
-      expected_categories =  Rails.version.starts_with?('4.2') ? Subscription.categories.values_at(:participating_discussions, :followed_discussions) : ['participating_discussions', 'followed_discussions']
+      expected_categories = ['participating_discussions', 'followed_discussions']
       it{ is_expected.to match_array expected_categories }
     end
 
     context 'with weekly' do
       let(:frequency){ :weekly }
       subject{ categories }
-      # TODO: When on Rails 5, Remove Version Checks(See L102 For Details)
-      expected_categories =  Rails.version.starts_with?('4.2') ? Subscription.categories.values_at(:messages, :started_discussions) : ['messages', 'started_discussions']
+      expected_categories = ['messages', 'started_discussions']
       it{ is_expected.to match_array expected_categories }
     end
 
diff --git a/spec/models/comment_spec.rb b/spec/models/comment_spec.rb
index 8eb14b7b..4e15d963 100644
--- a/spec/models/comment_spec.rb
+++ b/spec/models/comment_spec.rb
@@ -554,16 +554,8 @@ def mention(subject)
     let(:comment){ create :comment }
 
     it 'should queue the notification' do
-      # TODO: Once on Rails 5, Can Remove this Version Check
-      # In Rails Versions < 5, commit callbacks are not getting called in transactional tests.
-      # See https://stackoverflow.com/a/30901628/15768801 for more details.
-      if Rails.version.starts_with?('5')
-        allow(CommentSubscriptionWorker).to receive(:perform_async)
-        expect(CommentSubscriptionWorker).to have_received(:perform_async).with comment.id
-      else
-        expect(CommentSubscriptionWorker).to receive(:perform_async).with comment.id
-        comment.run_callbacks :commit
-      end
+      allow(CommentSubscriptionWorker).to receive(:perform_async)
+      expect(CommentSubscriptionWorker).to have_received(:perform_async).with comment.id
     end
   end
 
@@ -655,15 +647,9 @@ def mention(subject)
 
     describe '#publish_to_event_stream_later' do
       it 'should be triggered after a commit' do
-        # TODO: Once on Rails 5, Can Remove this Version Check
-        if Rails.version.starts_with?('5')
-          new_comment = build(:comment)
-          expect(new_comment).to receive :publish_to_event_stream_later
-          new_comment.save!
-        else
-          expect(comment).to receive :publish_to_event_stream_later
-          comment.run_callbacks :commit
-        end
+        new_comment = build(:comment)
+        expect(new_comment).to receive :publish_to_event_stream_later
+        new_comment.save!
       end
 
       it 'should enqueue the publish worker' do
diff --git a/spec/models/data_request_spec.rb b/spec/models/data_request_spec.rb
index a6150851..7774023a 100644
--- a/spec/models/data_request_spec.rb
+++ b/spec/models/data_request_spec.rb
@@ -75,19 +75,10 @@
 
   describe '#spawn_worker' do
     it 'should run the worker' do
-      # TODO: Once on Rails 5, Can Remove this Version Check
-      # In Rails Versions < 5, commit callbacks are not getting called in transactional tests.
-      # See https://stackoverflow.com/a/30901628/15768801 for more details.
-      if Rails.version.starts_with?('5')
-        allow(TagExportWorker).to receive(:perform_async)
-        data_request = build :tags_data_request
-        data_request.save!
-        expect(TagExportWorker).to have_received(:perform_async).with data_request.id
-      else
-        data_request = create :tags_data_request
-        expect(TagExportWorker).to receive(:perform_async).with data_request.id
-        data_request.run_callbacks :commit
-      end
+      allow(TagExportWorker).to receive(:perform_async)
+      data_request = build :tags_data_request
+      data_request.save!
+      expect(TagExportWorker).to have_received(:perform_async).with data_request.id
     end
   end
 
diff --git a/spec/models/discussion_spec.rb b/spec/models/discussion_spec.rb
index 0c4b3600..b4344fff 100644
--- a/spec/models/discussion_spec.rb
+++ b/spec/models/discussion_spec.rb
@@ -191,19 +191,10 @@ def create_discussion(position: nil)
 
   describe '#notify_subscribers_later' do
     it 'should queue the notification' do
-      # TODO: Once on Rails 5, Can Remove this Version Check
-      # In Rails Versions < 5, commit callbacks are not getting called in transactional tests.
-      # See https://stackoverflow.com/a/30901628/15768801 for more details.
-      if Rails.version.starts_with?('5')
-        allow(DiscussionSubscriptionWorker).to receive(:perform_async)
-        discussion = build :discussion
-        discussion.save!
-        expect(DiscussionSubscriptionWorker).to have_received(:perform_async).with discussion.id
-      else
-        discussion = create :discussion
-        expect(DiscussionSubscriptionWorker).to receive(:perform_async).with discussion.id
-        discussion.run_callbacks :commit
-      end
+      allow(DiscussionSubscriptionWorker).to receive(:perform_async)
+      discussion = build :discussion
+      discussion.save!
+      expect(DiscussionSubscriptionWorker).to have_received(:perform_async).with discussion.id
     end
   end
 
diff --git a/spec/models/group_mention_spec.rb b/spec/models/group_mention_spec.rb
index 20896cc0..6d8918f9 100644
--- a/spec/models/group_mention_spec.rb
+++ b/spec/models/group_mention_spec.rb
@@ -65,16 +65,9 @@
 
   describe '#notify_later' do
     it 'should queue the notification' do
-      # TODO: Once on Rails 5, Can Remove this Version Check
-      if Rails.version.starts_with?('5')
-        group_mention = build :group_mention
-        expect(GroupMentionWorker).to receive(:perform_async)
-        group_mention.save!
-      else
-        group_mention = create :group_mention
-        expect(GroupMentionWorker).to receive(:perform_async).with group_mention.id
-        group_mention.run_callbacks :commit
-      end
+      group_mention = build :group_mention
+      expect(GroupMentionWorker).to receive(:perform_async)
+      group_mention.save!
     end
   end
 
diff --git a/spec/models/mention_spec.rb b/spec/models/mention_spec.rb
index 3cacfe3f..279ac419 100644
--- a/spec/models/mention_spec.rb
+++ b/spec/models/mention_spec.rb
@@ -30,16 +30,9 @@
 
   describe '#notify_later' do
     it 'should queue the notification' do
-       # TODO: Once on Rails 5, Can Remove this Version Check
-       if Rails.version.starts_with?('5')
-        mention = build :mention, mentionable: focus
-        expect(MentionWorker).to receive(:perform_async)
-        mention.save!
-      else
-        mention = create :mention, mentionable: focus
-        expect(MentionWorker).to receive(:perform_async).with mention.id
-        mention.run_callbacks :commit
-      end
+      mention = build :mention, mentionable: focus
+      expect(MentionWorker).to receive(:perform_async)
+      mention.save!
     end
   end
 
diff --git a/spec/models/moderation_spec.rb b/spec/models/moderation_spec.rb
index 1d595be8..69dff78b 100644
--- a/spec/models/moderation_spec.rb
+++ b/spec/models/moderation_spec.rb
@@ -104,15 +104,9 @@
     include_context 'moderation subscriptions'
 
     it 'should queue the notification' do
-      # TODO: Once on Rails 5, Can Remove this Version Check
-      if Rails.version.starts_with?('5')
-        new_moderation = build :moderation, section: 'project-1'
-        expect(ModerationNotificationWorker).to receive(:perform_async)
-        new_moderation.save!
-      else
-        expect(ModerationNotificationWorker).to receive(:perform_async).with moderation.id
-        moderation.run_callbacks :commit
-      end
+      new_moderation = build :moderation, section: 'project-1'
+      expect(ModerationNotificationWorker).to receive(:perform_async)
+      new_moderation.save!
     end
   end