diff --git a/Gemfile.lock b/Gemfile.lock
index ed568f4e..bd2fd904 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -36,6 +36,7 @@ GEM
     byebug (11.1.3)
     childprocess (4.1.0)
     climate_control (1.2.0)
+    coderay (1.1.3)
     colorize (1.1.0)
     concurrent-ruby (1.2.2)
     coveralls_reborn (0.27.0)
@@ -115,6 +116,7 @@ GEM
     i18n (1.14.1)
       concurrent-ruby (~> 1.0)
     iniparse (1.5.0)
+    method_source (1.1.0)
     mini_portile2 (2.8.2)
     minitest (5.18.1)
     multipart-post (2.3.0)
@@ -133,6 +135,9 @@ GEM
       racc
     pd_ruby (0.2.3)
       colorize
+    pry (0.14.2)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
     public_suffix (5.0.1)
     racc (1.7.1)
     rack (3.0.8)
@@ -205,6 +210,7 @@ DEPENDENCIES
   factory_bot (~> 6.1.0)
   ledger_sync!
   overcommit (~> 0.57.0)
+  pry
   rake (~> 13.0)
   rspec (~> 3.2)
   rubocop (= 1.0.0)
diff --git a/ledger_sync.gemspec b/ledger_sync.gemspec
index 959dce96..2b17a5bc 100644
--- a/ledger_sync.gemspec
+++ b/ledger_sync.gemspec
@@ -38,6 +38,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency('coveralls_reborn')
   spec.add_development_dependency('factory_bot', '~> 6.1.0')
   spec.add_development_dependency('overcommit', '~> 0.57.0')
+  spec.add_development_dependency('pry')
   spec.add_development_dependency('rake', '~> 13.0')
   spec.add_development_dependency('rspec', '~> 3.2')
   spec.add_development_dependency('rubocop', '1.0.0')
diff --git a/lib/ledger_sync.rb b/lib/ledger_sync.rb
index 142eff8f..d630c61b 100644
--- a/lib/ledger_sync.rb
+++ b/lib/ledger_sync.rb
@@ -15,6 +15,7 @@
 require 'faraday'
 require 'tempfile'
 require 'pd_ruby'
+require 'pry'
 
 # Version
 require 'ledger_sync/version'
diff --git a/lib/ledger_sync/resource_attribute.rb b/lib/ledger_sync/resource_attribute.rb
index f9a75ce9..8e01b2e9 100644
--- a/lib/ledger_sync/resource_attribute.rb
+++ b/lib/ledger_sync/resource_attribute.rb
@@ -37,16 +37,16 @@ def assert_valid(args = {})
       value = args.fetch(:value)
 
       type.assert_valid(value: value)
-    rescue Error::TypeError::ValueClassError
-      raise ResourceAttributeError::TypeError.new(
-        attribute: self,
-        resource_class: resource_class,
-        value: value
-      )
+    # rescue Error::TypeError::ValueClassError
+    #   raise ResourceAttributeError::TypeError.new(
+    #     attribute: self,
+    #     resource_class: resource_class,
+    #     value: value
+    #   )
     end
 
     def cast(value)
-      type.cast(value: value)
+      cast_val(value)
     end
 
     # This is for ActiveModel::Dirty, since we define @attributes
@@ -65,12 +65,16 @@ def valid_with?(value:)
     end
 
     def value=(val)
-      @value = type.cast(value: val)
+      @value = cast_val(val)
     end
 
     def will_change?(val)
       assert_valid(value: val)
-      value != type.cast(value: val)
+      value != cast_val(val)
+    end
+
+    def cast_val(val)
+      type.cast(value: val)
     end
   end
 end
diff --git a/lib/ledger_sync/serialization/attribute.rb b/lib/ledger_sync/serialization/attribute.rb
index 6140770b..dc6a962e 100644
--- a/lib/ledger_sync/serialization/attribute.rb
+++ b/lib/ledger_sync/serialization/attribute.rb
@@ -6,6 +6,7 @@ module LedgerSync
   module Serialization
     class Attribute
       attr_reader :block,
+                  :default,
                   :hash_attribute,
                   :if_method,
                   :resource_attribute,
@@ -14,6 +15,7 @@ class Attribute
 
       def initialize(args = {})
         @block              = args.fetch(:block, nil)
+        @default            = args.fetch(:default, nil)
         @hash_attribute     = args.fetch(:hash_attribute, nil).try(:to_s)
         @resource_attribute = args.fetch(:resource_attribute, nil).try(:to_s)
         @resource_class     = args.fetch(:resource_class, nil)
diff --git a/lib/ledger_sync/serialization/deserializer_attribute.rb b/lib/ledger_sync/serialization/deserializer_attribute.rb
index 789c1e89..d8e174eb 100644
--- a/lib/ledger_sync/serialization/deserializer_attribute.rb
+++ b/lib/ledger_sync/serialization/deserializer_attribute.rb
@@ -31,9 +31,9 @@ def value_from_hash(hash:, resource:)
         value = hash.dig(*hash_attribute.split('.'))
 
         if type.is_a?(Type::DeserializerType)
-          type.cast(deserializer_attribute: self, resource: resource, value: value)
+          type.cast(deserializer_attribute: self, resource: resource, value: value, default: default)
         else
-          value = type.cast(value: value)
+          value = type.cast(value: value, default: default)
           return value if resource_attribute_dot_parts.count <= 1
 
           nested_resource = resource.send(resource_attribute_dot_parts.first)
diff --git a/lib/ledger_sync/serialization/mixin.rb b/lib/ledger_sync/serialization/mixin.rb
index d7fc546c..6217be97 100644
--- a/lib/ledger_sync/serialization/mixin.rb
+++ b/lib/ledger_sync/serialization/mixin.rb
@@ -47,6 +47,7 @@ def _build_attribute(args)
           serializer         = args.fetch(:serializer, nil)
           type               = args.fetch(:type, nil)
           if_method          = args.fetch(:if, nil)
+          default            = args.fetch(:default, nil)
 
           attribute_class.new(
             block: block,
@@ -55,7 +56,8 @@ def _build_attribute(args)
             resource_attribute: resource_attribute,
             resource_class: resource_class,
             serializer: serializer,
-            type: type
+            type: type,
+            default: default
           )
         end
       end
diff --git a/lib/ledger_sync/serialization/type/deserializer_references_many_type.rb b/lib/ledger_sync/serialization/type/deserializer_references_many_type.rb
index 828d0f5a..15099d69 100644
--- a/lib/ledger_sync/serialization/type/deserializer_references_many_type.rb
+++ b/lib/ledger_sync/serialization/type/deserializer_references_many_type.rb
@@ -10,8 +10,9 @@ def cast_value(args = {})
           deserializer_attribute = args.fetch(:deserializer_attribute)
           value                  = args.fetch(:value)
           resource               = args.fetch(:resource)
+          default                = args.fetch(:default, nil)
 
-          return if value.nil?
+          return default if value.nil?
 
           first_dot = deserializer_attribute.resource_attribute_dot_parts.first.to_sym
           nested_resource = resource.class.resource_attributes[first_dot].type.resource_class.new
diff --git a/lib/ledger_sync/serialization/type/deserializer_type.rb b/lib/ledger_sync/serialization/type/deserializer_type.rb
index 8e298b70..7bbbfff1 100644
--- a/lib/ledger_sync/serialization/type/deserializer_type.rb
+++ b/lib/ledger_sync/serialization/type/deserializer_type.rb
@@ -16,12 +16,14 @@ def cast_value(args = {})
           deserializer_attribute = args.fetch(:deserializer_attribute)
           resource               = args.fetch(:resource)
           value                  = args.fetch(:value)
+          default                = args.fetch(:default, nil)
+
+          return default if value.nil?
 
           first_dot = deserializer_attribute.resource_attribute_dot_parts.first.to_sym
           nested_resource = resource.send(first_dot)
           nested_resource ||= resource.class.resource_attributes[first_dot].type.resource_class.new
 
-          return if value.nil?
 
           deserializer.new.deserialize(hash: value, resource: nested_resource)
         end
diff --git a/lib/ledger_sync/type/reference_many.rb b/lib/ledger_sync/type/reference_many.rb
index 626f66a6..30a725c6 100644
--- a/lib/ledger_sync/type/reference_many.rb
+++ b/lib/ledger_sync/type/reference_many.rb
@@ -16,7 +16,10 @@ def initialize(resource_class:)
 
       def cast(args = {})
         value = args.fetch(:value)
-        return if value.nil?
+        default = args.fetch(:default, nil)
+
+        pd default
+        return default if value.nil?
 
         many_array_class = LedgerSync::ResourceAttribute::Reference::Many::ManyArray
 
@@ -33,7 +36,9 @@ def type
       end
 
       def valid?(args = {})
-        value = args.fetch(:value)
+        pd args
+        value = args.fetch(:value, args.fetch(:default, nil))
+
         return false unless value.is_a?(Array)
         return true if (resource_classes & value.map(&:class)).any?
         return true if value.is_a?(Array) && value.empty?
diff --git a/lib/ledger_sync/type/value_mixin.rb b/lib/ledger_sync/type/value_mixin.rb
index 937108b4..793c6728 100644
--- a/lib/ledger_sync/type/value_mixin.rb
+++ b/lib/ledger_sync/type/value_mixin.rb
@@ -9,6 +9,8 @@ def self.included(base)
       end
 
       def assert_valid(args = {})
+        pd self
+        pd valid?(args)
         return if valid?(args)
 
         value = args.fetch(:value)
@@ -22,7 +24,8 @@ def assert_valid(args = {})
       # Do not override this method.  Override private method cast_value
       def cast(args = {})
         assert_valid(args)
-        return nil if args.fetch(:value).nil?
+
+        return args.fetch(:default, nil) if args.fetch(:value).nil?
 
         cast_value(args)
       end
@@ -41,10 +44,16 @@ def cast_value(args = {})
       end
 
       def valid_class?(args = {})
-        value = args.fetch(:value)
+        # value = args.fetch(:value)
+        value = args.fetch(:value, args.fetch(:default, nil))
+        pd args
+        pd value
+        pd value.nil?
 
         return true if value.nil?
+        pd
         return true if valid_classes.select { |e| value.is_a?(e) }.any?
+        pd
 
         false
       end
diff --git a/spec/deserializer_spec.rb b/spec/deserializer_spec.rb
index 6cf219b0..330c938e 100644
--- a/spec/deserializer_spec.rb
+++ b/spec/deserializer_spec.rb
@@ -11,6 +11,26 @@
     end
   end
 
+  let(:references_many_deserializer_class) do
+    Class.new(LedgerSync::Deserializer) do
+      references_many :objs, deserializer: LedgerSync::Ledgers::TestLedger::Subsidiary::Deserializer
+    end
+  end
+
+  let(:references_many_deserializer) do
+    references_many_deserializer_class.new
+  end
+
+  let(:references_many_with_default_deserializer_class) do
+    Class.new(LedgerSync::Deserializer) do
+      references_many :objs, deserializer: LedgerSync::Ledgers::TestLedger::Subsidiary::Deserializer, default: []
+    end
+  end
+
+  let(:references_many_with_default_deserializer) do
+    references_many_with_default_deserializer_class.new
+  end
+
   let(:custom_deserializer_class) do
     Class.new(LedgerSync::Deserializer) do
       attribute :foo,
@@ -38,10 +58,40 @@
         name
         phone_number
         type
-      ]
+      ],
+      references_many: [
+        [:objs]
+      ],
+      reference_class: LedgerSync::Ledgers::TestLedger::Subsidiary
     )
   end
 
+  # let(:custom_references_nany_resource_class) do
+  #   Object.const_set(
+  #     test_resource_class_name,
+  #     Class.new(LedgerSync::Resource) do
+  #       references_many :objs, to: LedgerSync::Ledgers::TestLedger::Subsidiary::Deserializer
+  #     end
+  #   )
+  # end
+
+  # let(:test_references_many_resource) do
+  #   custom_references_nany_resource_class.new
+  # end
+
+  # let(:custom_references_nany_with_default_resource_class) do
+  #   Object.const_set(
+  #     test_resource_class_name,
+  #     Class.new(LedgerSync::Resource) do
+  #       references_many :objs, to: LedgerSync::Ledgers::TestLedger::Subsidiary::Deserializer, default: []
+  #     end
+  #   )
+  # end
+
+  # let(:test_references_many_with_default_resource) do
+  #   custom_references_nany_resource_class.new
+  # end
+
   it { expect(described_class).to respond_to(:attribute) }
   it { expect(described_class).to respond_to(:references_many) }
   it { expect(described_class).to respond_to(:references_one) }
@@ -142,5 +192,18 @@
         expect(dresource.foo).to eq('asdf')
       end
     end
+
+    context 'with references_many' do
+      it do
+        dresource = references_many_deserializer.deserialize(hash: {}, resource: test_resource)
+        expect(dresource.objs).to eq(nil)
+      end
+
+      it do
+        # binding.pry
+        dresource = references_many_with_default_deserializer.deserialize(hash: {}, resource: test_resource)
+        expect(dresource.objs).to eq([])
+      end
+    end
   end
 end
diff --git a/spec/support/resource_helpers.rb b/spec/support/resource_helpers.rb
index b4a58c15..4b47bfc6 100644
--- a/spec/support/resource_helpers.rb
+++ b/spec/support/resource_helpers.rb
@@ -1,8 +1,12 @@
 # frozen_string_literal: true
 
 module ResourceHelpers
+  def test_resource_class_name
+    "#{test_run_id}TestCustomResource#{test_resource_counter_increment!}"
+  end
+
   def new_resource_class(args = {}) # rubocop:disable Metrics/CyclomaticComplexity
-    class_name = args.fetch(:name, "#{test_run_id}TestCustomResource#{test_resource_counter_increment!}")
+    class_name = args.fetch(:name, test_resource_class_name)
 
     remove_customer_resource_class(class_name: class_name)
 
@@ -31,9 +35,9 @@ def new_resource_class(args = {}) # rubocop:disable Metrics/CyclomaticComplexity
           references_one a[0], **{ to: reference_class }.merge(a[1] || {})
         end
 
-        references_many = args.fetch(:references_many, [])
-        references_many = Array(references_many)
-        references_many.each do |a|
+        references_manies = args.fetch(:references_many, [])
+        references_manies = Array(references_manies)
+        references_manies.each do |a|
           a = Array(a)
           references_many a[0], **{ to: reference_class }.merge(a[1] || {})
         end