diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4cc4c01c..ad8ad929 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,8 @@ Features:
 - [#1050](https://github.com/rails-api/active_model_serializers/pull/1050) Add support for toplevel jsonapi member (@beauby, @bf4)
 - [#1251](https://github.com/rails-api/active_model_serializers/pull/1251) Rename ArraySerializer to
     CollectionSerializer for clarity, add ActiveModelSerializers.config.collection_serializer (@bf4)
+- [#1295](https://github.com/rails-api/active_model_serializers/pull/1295) Add config `serializer_lookup_enabled` that,
+  when disabled, requires serializers to explicitly specified. (@trek)
 
 Fixes:
 - [#1239](https://github.com/rails-api/active_model_serializers/pull/1239) Fix duplicates in JSON API compound documents (@beauby)
diff --git a/docs/general/configuration_options.md b/docs/general/configuration_options.md
index 46465f06..1632324d 100644
--- a/docs/general/configuration_options.md
+++ b/docs/general/configuration_options.md
@@ -5,6 +5,7 @@ The following configuration options can be set on `ActiveModel::Serializer.confi
 ## General
 
 - `adapter`: The [adapter](adapters.md) to use. Possible values: `:attributes, :json, :json_api`. Default: `:attributes`.
+- `serializer_lookup_enabled`: When `false`, serializers must be explicitly specified. Default: `true`
 
 ## JSON API
 
diff --git a/lib/action_controller/serialization.rb b/lib/action_controller/serialization.rb
index 5fefaedf..fb5a03a3 100644
--- a/lib/action_controller/serialization.rb
+++ b/lib/action_controller/serialization.rb
@@ -10,6 +10,12 @@ module ActionController
     # Deprecated
     ADAPTER_OPTION_KEYS = ActiveModel::SerializableResource::ADAPTER_OPTION_KEYS
 
+    module ClassMethods
+      def serialization_scope(scope)
+        self._serialization_scope = scope
+      end
+    end
+
     included do
       class_attribute :_serialization_scope
       self._serialization_scope = :current_user
@@ -55,11 +61,5 @@ module ActionController
         super(serializable_resource, options)
       end
     end
-
-    module ClassMethods
-      def serialization_scope(scope)
-        self._serialization_scope = scope
-      end
-    end
   end
 end
diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index eadcb32e..48f57edc 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -172,6 +172,7 @@ module ActiveModel
     #   2. try again with superclass, if present
     #   3. nil
     def self.get_serializer_for(klass)
+      return nil unless config.serializer_lookup_enabled
       serializers_cache.fetch_or_store(klass) do
         # NOTE(beauby): When we drop 1.9.3 support we can lazify the map for perfs.
         serializer_class = serializer_lookup_chain_for(klass).map(&:safe_constantize).find { |x| x && x < ActiveModel::Serializer }
diff --git a/lib/active_model/serializer/configuration.rb b/lib/active_model/serializer/configuration.rb
index 9e33633e..520f76f2 100644
--- a/lib/active_model/serializer/configuration.rb
+++ b/lib/active_model/serializer/configuration.rb
@@ -9,6 +9,7 @@ module ActiveModel
       included do |base|
         config = base.config
         config.collection_serializer = ActiveModel::Serializer::CollectionSerializer
+        config.serializer_lookup_enabled = true
 
         def config.array_serializer=(collection_serializer)
           self.collection_serializer = collection_serializer
diff --git a/test/serializers/serializer_for_test.rb b/test/serializers/serializer_for_test.rb
index 53b2f07d..89cbd199 100644
--- a/test/serializers/serializer_for_test.rb
+++ b/test/serializers/serializer_for_test.rb
@@ -57,7 +57,7 @@ module ActiveModel
 
         def test_serializer_for_non_ams_serializer
           serializer = ActiveModel::Serializer.serializer_for(@tweet)
-          assert_nil(serializer)
+          assert_equal nil, serializer
         end
 
         def test_serializer_for_existing_serializer
@@ -65,6 +65,13 @@ module ActiveModel
           assert_equal ProfileSerializer, serializer
         end
 
+        def test_serializer_for_existing_serializer_with_lookup_disabled
+          serializer = with_serializer_lookup_disabled do
+            ActiveModel::Serializer.serializer_for(@profile)
+          end
+          assert_equal nil, serializer
+        end
+
         def test_serializer_for_not_existing_serializer
           serializer = ActiveModel::Serializer.serializer_for(@model)
           assert_equal nil, serializer
@@ -75,21 +82,51 @@ module ActiveModel
           assert_equal ProfileSerializer, serializer
         end
 
+        def test_serializer_inherited_serializer_with_lookup_disabled
+          serializer = with_serializer_lookup_disabled do
+            ActiveModel::Serializer.serializer_for(@my_profile)
+          end
+          assert_equal nil, serializer
+        end
+
         def test_serializer_custom_serializer
           serializer = ActiveModel::Serializer.serializer_for(@custom_profile)
           assert_equal ProfileSerializer, serializer
         end
 
+        def test_serializer_custom_serializer_with_lookup_disabled
+          serializer = with_serializer_lookup_disabled do
+            ActiveModel::Serializer.serializer_for(@custom_profile)
+          end
+          assert_equal ProfileSerializer, serializer
+        end
+
         def test_serializer_for_namespaced_resource
           post = ResourceNamespace::Post.new
           serializer = ActiveModel::Serializer.serializer_for(post)
-          assert_equal(ResourceNamespace::PostSerializer, serializer)
+          assert_equal ResourceNamespace::PostSerializer, serializer
+        end
+
+        def test_serializer_for_namespaced_resource_with_lookup_disabled
+          post = ResourceNamespace::Post.new
+          serializer = with_serializer_lookup_disabled do
+            ActiveModel::Serializer.serializer_for(post)
+          end
+          assert_equal nil, serializer
         end
 
         def test_serializer_for_nested_resource
           comment = ResourceNamespace::Comment.new
           serializer = ResourceNamespace::PostSerializer.serializer_for(comment)
-          assert_equal(ResourceNamespace::PostSerializer::CommentSerializer, serializer)
+          assert_equal ResourceNamespace::PostSerializer::CommentSerializer, serializer
+        end
+
+        def test_serializer_for_nested_resource_with_lookup_disabled
+          comment = ResourceNamespace::Comment.new
+          serializer = with_serializer_lookup_disabled do
+            ResourceNamespace::PostSerializer.serializer_for(comment)
+          end
+          assert_equal nil, serializer
         end
       end
     end
diff --git a/test/support/serialization_testing.rb b/test/support/serialization_testing.rb
index e1272097..84853e2b 100644
--- a/test/support/serialization_testing.rb
+++ b/test/support/serialization_testing.rb
@@ -31,6 +31,14 @@ module SerializationTesting
     ActiveModel::Serializer.config.replace(old_config)
   end
 
+  def with_serializer_lookup_disabled
+    original_serializer_lookup = ActiveModelSerializers.config.serializer_lookup_enabled
+    ActiveModelSerializers.config.serializer_lookup_enabled = false
+    yield
+  ensure
+    ActiveModelSerializers.config.serializer_lookup_enabled = original_serializer_lookup
+  end
+
   def serializable(resource, options = {})
     ActiveModel::SerializableResource.new(resource, options)
   end