diff --git a/lib/docurest/field.rb b/lib/docurest/field.rb
new file mode 100644
index 0000000..e4ccad4
--- /dev/null
+++ b/lib/docurest/field.rb
@@ -0,0 +1,40 @@
+require "docurest/field/base"
+require "docurest/field/boolean"
+require "docurest/field/date_time"
+require "docurest/field/integer"
+require "docurest/field/float"
+
+module Docurest
+  module Field
+    CONVERSION = {
+      boolean: Docurest::Field::Boolean,
+      integer: Docurest::Field::Integer,
+      float: Docurest::Field::Float,
+      date_time: Docurest::Field::DateTime,
+    }
+
+    def field(name, docusign_name = nil, type = nil)
+      attr_accessor name
+      if docusign_name
+        alias_method docusign_name, name
+        define_method("#{docusign_name}=") do |value|
+          value = if type.is_a?(Proc)
+            type.call value
+          elsif CONVERSION.key?(type)
+            CONVERSION[type].new(value).convert
+          else
+            value
+          end
+          send("#{name}=", value)
+        end
+      end
+    end
+
+    def association(klass, &block)
+      define_method(klass) do
+        instance_variable_get(:"@#{klass}") ||
+          instance_variable_set(:"@#{klass}", persisted? ? instance_eval(&block) : [])
+      end
+    end
+  end
+end
diff --git a/lib/docurest/field/base.rb b/lib/docurest/field/base.rb
new file mode 100644
index 0000000..fedebbf
--- /dev/null
+++ b/lib/docurest/field/base.rb
@@ -0,0 +1,6 @@
+module Docurest
+  module Field
+    class Base < Struct.new(:value)
+    end
+  end
+end
diff --git a/lib/docurest/field/boolean.rb b/lib/docurest/field/boolean.rb
new file mode 100644
index 0000000..93d37c0
--- /dev/null
+++ b/lib/docurest/field/boolean.rb
@@ -0,0 +1,9 @@
+module Docurest
+  module Field
+    class Boolean < Docurest::Field::Base
+      def convert
+        value == "true" ? true : false
+      end
+    end
+  end
+end
diff --git a/lib/docurest/field/date_time.rb b/lib/docurest/field/date_time.rb
new file mode 100644
index 0000000..693483e
--- /dev/null
+++ b/lib/docurest/field/date_time.rb
@@ -0,0 +1,9 @@
+module Docurest
+  module Field
+    class DateTime < Docurest::Field::Base
+      def convert
+        ::DateTime.parse(value)
+      end
+    end
+  end
+end
diff --git a/lib/docurest/field/float.rb b/lib/docurest/field/float.rb
new file mode 100644
index 0000000..805f4a1
--- /dev/null
+++ b/lib/docurest/field/float.rb
@@ -0,0 +1,9 @@
+module Docurest
+  module Field
+    class Float < Docurest::Field::Base
+      def convert
+        value.to_f
+      end
+    end
+  end
+end
diff --git a/lib/docurest/field/integer.rb b/lib/docurest/field/integer.rb
new file mode 100644
index 0000000..1e797c4
--- /dev/null
+++ b/lib/docurest/field/integer.rb
@@ -0,0 +1,9 @@
+module Docurest
+  module Field
+    class Integer < Docurest::Field::Base
+      def convert
+        value.to_i
+      end
+    end
+  end
+end