diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
index 8e1ad5bd2c..8239f2595f 100644
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,6 +1,7 @@
 Next Release
 ============
 
+* [#236](https://github.com/intridea/grape/pull/236): Allow validation of nested parameters. - [@tim-vandecasteele](https://github.com/tim-vandecasteele).
 * [#201](https://github.com/intridea/grape/pull/201): Added custom exceptions to Grape. Updated validations to use ValidationError that can be rescued. - [@adamgotterer](https://github.com/adamgotterer).
 * [#211](https://github.com/intridea/grape/pull/211): Updates to validation and coercion: Fix #211 and force order of operations for presence and coercion - [@adamgotterer](https://github.com/adamgotterer).
 * [#210](https://github.com/intridea/grape/pull/210): Fix: `Endpoint#body_params` causing undefined method 'size' - [@adamgotterer](https://github.com/adamgotterer).
@@ -10,6 +11,7 @@ Next Release
 * [#203](https://github.com/intridea/grape/pull/203): Added a check to `Entity#serializable_hash` that verifies an entity exists on an object - [@adamgotterer](https://github.com/adamgotterer).
 * [#204](https://github.com/intridea/grape/pull/204): Added ability to declare shared parameters at namespace level - [@tim-vandecasteele](https://github.com/tim-vandecasteele).
 * [#208](https://github.com/intridea/grape/pull/208): `Entity#serializable_hash` must also check if attribute is generated by a user supplied block - [@ppadron](https://github.com/ppadron).
+* [#234](https://github.com/intridea/grape/pull/234): Adds a DSL for creating entities via mixin - [@mbleigh](https://github.com/mbleigh).
 
 0.2.1 (7/11/2012)
 =================
diff --git a/README.markdown b/README.markdown
index dfc83493ab..558de1004e 100644
--- a/README.markdown
+++ b/README.markdown
@@ -220,6 +220,11 @@ You can define validations and coercion options for your parameters using `param
 params do
   requires :id, type: Integer
   optional :name, type: String, regexp: /^[a-z]+$/
+
+  group :user do
+    requires :first_name
+    requires :last_name
+  end
 end
 get ':id' do
   # params[:id] is an Integer
@@ -229,6 +234,9 @@ end
 When a type is specified an implicit validation is done after the coercion to ensure 
 the output type is the one declared.
 
+Parameters can be nested using `group`. In the above example, this means both
+`params[:user][:first_name]` and `params[:user][:last_name]` are required next to `params[:id]`.
+
 ### Namespace Validation and Coercion
 Namespaces allow parameter definitions and apply to every method within the namespace.
 
@@ -604,6 +612,27 @@ module API
 end
 ```
 
+#### Using the Exposure DSL
+
+Grape ships with a DSL to easily define entities within the context
+of an existing class:
+
+```ruby
+class User
+  include Grape::Entity::DSL
+
+  entity :name, :email do
+    expose :advanced, if: :conditional
+  end
+end
+```
+
+The above will automatically create a `User::Entity` class and
+define properties on it according to the same rules as above. If
+you only want to define simple exposures you don't have to supply
+a block and can instead simply supply a list of comma-separated
+symbols.
+
 ### Using Entities
 
 Once an entity is defined, it can be used within endpoints, by calling #present. The #present
@@ -629,6 +658,32 @@ module API
 end
 ```
 
+### Entity Organization
+
+In addition to separately organizing entities, it may be useful to
+put them as namespaced classes underneath the model they represent.
+For example:
+
+```ruby
+class User
+  def entity
+    Entity.new(self)
+  end
+
+  class Entity < Grape::Entity
+    expose :name, :email
+  end
+end
+```
+
+If you organize your entities this way, Grape will automatically
+detect the `Entity` class and use it to present your models. In
+this example, if you added `present User.new` to your endpoint,
+Grape would automatically detect that there is a `User::Entity`
+class and use that as the representative entity. This can still
+be overridden by using the `:with` option or an explicit
+`represents` call.
+
 ### Caveats
 
 Entities with duplicate exposure names and conditions will silently overwrite one another.
diff --git a/lib/grape/api.rb b/lib/grape/api.rb
index 6b314b0c9d..17d55f7acb 100644
--- a/lib/grape/api.rb
+++ b/lib/grape/api.rb
@@ -386,6 +386,7 @@ def nest(*blocks, &block)
           instance_eval &block if block_given?
           blocks.each{|b| instance_eval &b}
           settings.pop   # when finished, we pop the context
+          reset_validations!
         else
           instance_eval &block
         end
diff --git a/lib/grape/endpoint.rb b/lib/grape/endpoint.rb
index 535cf46395..8216cad1e1 100644
--- a/lib/grape/endpoint.rb
+++ b/lib/grape/endpoint.rb
@@ -255,6 +255,8 @@ def present(object, options = {})
         entity_class ||= (settings[:representations] || {})[potential]
       end
 
+      entity_class ||= object.class.const_get(:Entity) if object.class.const_defined?(:Entity)
+
       root = options.delete(:root)
 
       representation = if entity_class
diff --git a/lib/grape/entity.rb b/lib/grape/entity.rb
index ee114cedce..72c0cf9e70 100644
--- a/lib/grape/entity.rb
+++ b/lib/grape/entity.rb
@@ -43,6 +43,60 @@ module Grape
   class Entity
     attr_reader :object, :options
 
+    # The Entity DSL allows you to mix entity functionality into
+    # your existing classes.
+    module DSL
+      def self.included(base)
+        base.extend ClassMethods
+        ancestor_entity_class = base.ancestors.detect{|a| a.entity_class if a.respond_to?(:entity_class)}
+        base.const_set(:Entity, Class.new(ancestor_entity_class || Grape::Entity)) unless const_defined?(:Entity)
+      end
+
+      module ClassMethods
+        # Returns the automatically-created entity class for this
+        # Class.
+        def entity_class(search_ancestors=true)
+          klass = const_get(:Entity) if const_defined?(:Entity)
+          klass ||= ancestors.detect{|a| a.entity_class(false) if a.respond_to?(:entity_class) } if search_ancestors
+          klass
+        end
+
+        # Call this to make exposures to the entity for this Class.
+        # Can be called with symbols for the attributes to expose,
+        # a block that yields the full Entity DSL (See Grape::Entity),
+        # or both.
+        #
+        # @example Symbols only.
+        #
+        #   class User
+        #     include Grape::Entity::DSL
+        #     
+        #     entity :name, :email
+        #   end
+        #
+        # @example Mixed.
+        #
+        #   class User
+        #     include Grape::Entity::DSL
+        #     
+        #     entity :name, :email do
+        #       expose :latest_status, using: Status::Entity, if: :include_status
+        #       expose :new_attribute, :if => {:version => 'v2'}
+        #     end
+        #   end
+        def entity(*exposures, &block)
+          entity_class.expose *exposures if exposures.any?
+          entity_class.class_eval(&block) if block_given?
+          entity_class
+        end
+      end
+
+      # Instantiates an entity version of this object.
+      def entity
+        self.class.entity_class.new(self)
+      end
+    end
+
     # This method is the primary means by which you will declare what attributes
     # should be exposed by the entity.
     #
@@ -259,7 +313,7 @@ def serializable_hash(runtime_options = {})
       return nil if object.nil?
       opts = options.merge(runtime_options || {})
       exposures.inject({}) do |output, (attribute, exposure_options)|
-        if exposure_options.has_key?(:proc) || object.respond_to?(attribute) && conditions_met?(exposure_options, opts)
+        if (exposure_options.has_key?(:proc) || object.respond_to?(attribute)) && conditions_met?(exposure_options, opts)
           partial_output = value_for(attribute, opts)
           output[key_for(attribute)] =
             if partial_output.respond_to? :serializable_hash
diff --git a/lib/grape/validations.rb b/lib/grape/validations.rb
index 6ae6ec2636..687c4fa49e 100644
--- a/lib/grape/validations.rb
+++ b/lib/grape/validations.rb
@@ -8,9 +8,10 @@ module Validations
     # All validators must inherit from this class.
     # 
     class Validator
-      def initialize(attrs, options, required)
+      def initialize(attrs, options, required, scope)
         @attrs = Array(attrs)
         @required = required
+        @scope = scope
 
         if options.is_a?(Hash) && !options.empty?
           raise "unknown options: #{options.keys}"
@@ -18,6 +19,8 @@ def initialize(attrs, options, required)
       end
 
       def validate!(params)
+        params = @scope.params(params)
+
         @attrs.each do |attr_name|
           if @required || params.has_key?(attr_name)
             validate_param!(attr_name, params)
@@ -40,7 +43,7 @@ def self.convert_to_short_name(klass)
     ##
     # Base class for all validators taking only one param.
     class SingleOptionValidator < Validator
-      def initialize(attrs, options, required)
+      def initialize(attrs, options, required, scope)
         @option = options
         super
       end
@@ -67,7 +70,11 @@ def self.register_validator(short_name, klass)
     end
     
     class ParamsScope
-      def initialize(api, &block)
+      attr_accessor :element, :parent
+
+      def initialize(api, element, parent, &block)
+        @element = element
+        @parent = parent
         @api = api
         instance_eval(&block)
       end
@@ -89,7 +96,22 @@ def optional(*attrs)
         
         validates(attrs, validations)
       end
-      
+
+      def group(element, &block)
+        scope = ParamsScope.new(@api, element, self, &block)
+      end
+
+      def params(params)
+        params = @parent.params(params) if @parent
+        params = params[@element] || {} if @element
+        params
+      end
+
+      def full_name(name)
+        return "#{@parent.full_name(@element)}[#{name}]" if @parent
+        name.to_s
+      end
+
     private
       def validates(attrs, validations)
         doc_attrs = { :required => validations.keys.include?(:presence) }
@@ -106,9 +128,10 @@ def validates(attrs, validations)
         if desc = validations.delete(:desc)
           doc_attrs[:desc] = desc
         end
-        
-        @api.document_attribute(attrs, doc_attrs)
-        
+
+        full_attrs = attrs.collect{ |name| { :name => name, :full_name => full_name(name)} }
+        @api.document_attribute(full_attrs, doc_attrs)
+
         # Validate for presence before any other validators
         if validations.has_key?(:presence) && validations[:presence]
           validate('presence', validations[:presence], attrs, doc_attrs)
@@ -130,7 +153,7 @@ def validates(attrs, validations)
       def validate(type, options, attrs, doc_attrs)
         validator_class = Validations::validators[type.to_s]
         if validator_class
-          @api.settings[:validations] << validator_class.new(attrs, options, doc_attrs[:required])
+          @api.settings[:validations] << validator_class.new(attrs, options, doc_attrs[:required], self)
         else
           raise "unknown validator: #{type}"
         end
@@ -145,17 +168,16 @@ def reset_validations!
       end
       
       def params(&block)
-        ParamsScope.new(self, &block)
+        ParamsScope.new(self, nil, nil, &block)
       end
       
       def document_attribute(names, opts)
-        if @last_description
-          @last_description[:params] ||= {}
-        
-          Array(names).each do |name|
-            @last_description[:params][name.to_s] ||= {}
-            @last_description[:params][name.to_s].merge!(opts)
-          end
+        @last_description ||= {}
+        @last_description[:params] ||= {}
+
+        Array(names).each do |name|
+          @last_description[:params][name[:name].to_s] ||= {}
+          @last_description[:params][name[:name].to_s].merge!(opts).merge!({:full_name => name[:full_name]})
         end
       end
       
diff --git a/spec/grape/api_spec.rb b/spec/grape/api_spec.rb
index afb08cc852..3d88623b4f 100644
--- a/spec/grape/api_spec.rb
+++ b/spec/grape/api_spec.rb
@@ -1029,7 +1029,7 @@ class CommunicationError < RuntimeError; end
       subject.routes.map { |route|
         { :description => route.route_description, :params => route.route_params }
       }.should eq [
-        { :description => "method", :params => { "ns_param" => { :required => true, :desc => "namespace parameter" }, "method_param" => { :required => false, :desc => "method parameter" } } }
+        { :description => "method", :params => { "ns_param" => { :required => true, :desc => "namespace parameter", :full_name=>"ns_param" }, "method_param" => { :required => false, :desc => "method parameter", :full_name=>"method_param" } } }
       ]
     end
     it "should merge the parameters of nested namespaces" do
@@ -1055,7 +1055,33 @@ class CommunicationError < RuntimeError; end
       subject.routes.map { |route|
         { :description => route.route_description, :params => route.route_params }
       }.should eq [
-        { :description => "method", :params => { "ns_param" => { :required => true, :desc => "ns param 2" }, "ns1_param" => { :required => true, :desc => "ns1 param" }, "ns2_param" => { :required => true, :desc => "ns2 param" }, "method_param" => { :required => false, :desc => "method param" } } }
+        { :description => "method", :params => { "ns_param" => { :required => true, :desc => "ns param 2", :full_name=>"ns_param" }, "ns1_param" => { :required => true, :desc => "ns1 param", :full_name=>"ns1_param" }, "ns2_param" => { :required => true, :desc => "ns2 param", :full_name=>"ns2_param" }, "method_param" => { :required => false, :desc => "method param", :full_name=>"method_param" } } }
+      ]
+    end
+    it "should provide a full_name for parameters in nested groups" do
+      subject.desc "nesting"
+      subject.params do
+        requires :root_param, :desc => "root param"
+        group :nested do
+          requires :nested_param, :desc => "nested param"
+        end
+      end
+      subject.get "method" do ; end
+      subject.routes.map { |route|
+        { :description => route.route_description, :params => route.route_params }
+      }.should eq [
+        { :description => "nesting", :params => { "root_param" => { :required => true, :desc => "root param", :full_name=>"root_param" }, "nested_param" => { :required => true, :desc => "nested param", :full_name=>"nested[nested_param]" } } }
+      ]
+    end
+    it "should parse parameters when no description is given" do
+      subject.params do
+        requires :one_param, :desc => "one param"
+      end
+      subject.get "method" do ; end
+      subject.routes.map { |route|
+        { :description => route.route_description, :params => route.route_params }
+      }.should eq [
+        { :description => nil, :params => { "one_param" => { :required => true, :desc => "one param", :full_name=>"one_param" } } }
       ]
     end
     it "should not symbolize params" do
diff --git a/spec/grape/endpoint_spec.rb b/spec/grape/endpoint_spec.rb
index d6ff1c5e4e..0f27fbb174 100644
--- a/spec/grape/endpoint_spec.rb
+++ b/spec/grape/endpoint_spec.rb
@@ -347,6 +347,20 @@ def memoized
       last_response.body.should == 'Hiya'
     end
 
+    it 'should automatically use Klass::Entity if that exists' do
+      some_model = Class.new
+      entity = Class.new(Grape::Entity)
+      entity.stub!(:represent).and_return("Auto-detect!")
+
+      some_model.const_set :Entity, entity
+
+      subject.get '/example' do
+        present some_model.new
+      end
+      get '/example'
+      last_response.body.should == 'Auto-detect!'
+    end
+
     it 'should add a root key to the output if one is given' do
       subject.get '/example' do
         present({:abc => 'def'}, :root => :root)
diff --git a/spec/grape/entity_spec.rb b/spec/grape/entity_spec.rb
index a108f0c53e..198e3710e0 100644
--- a/spec/grape/entity_spec.rb
+++ b/spec/grape/entity_spec.rb
@@ -253,8 +253,6 @@
 
     describe '#serializable_hash' do
 
-
-
       it 'should not throw an exception if a nil options object is passed' do
         expect{ fresh_class.new(model).serializable_hash(nil) }.not_to raise_error
       end
@@ -296,6 +294,14 @@
         res = fresh_class.new(model).serializable_hash
         res.should have_key :non_existant_attribute
       end
+
+      it "should not expose attributes that are generated by a block but have not passed criteria" do
+        fresh_class.expose :non_existant_attribute, :proc => lambda {|model, options|
+          "I exist, but it is not yet my time to shine"
+        }, :if => lambda { |model, options| false }
+        res = fresh_class.new(model).serializable_hash
+        res.should_not have_key :non_existant_attribute
+      end
       
       context "#serializable_hash" do
       
@@ -472,5 +478,53 @@ class FriendEntity < Grape::Entity
         subject.send(:conditions_met?, exposure_options, :true => true).should be_false
       end
     end
+
+    describe "::DSL" do
+      subject{ Class.new }
+
+      it 'should create an Entity class when called' do
+        subject.should_not be_const_defined(:Entity)
+        subject.send(:include, Grape::Entity::DSL)
+        subject.should be_const_defined(:Entity)
+      end
+
+      context 'pre-mixed' do
+        before{ subject.send(:include, Grape::Entity::DSL) }
+
+        it 'should be able to define entity traits through DSL' do
+          subject.entity do
+            expose :name
+          end
+
+          subject.entity_class.exposures.should_not be_empty
+        end
+
+        it 'should be able to expose straight from the class' do
+          subject.entity :name, :email
+          subject.entity_class.exposures.size.should == 2
+        end
+
+        it 'should be able to mix field and advanced exposures' do
+          subject.entity :name, :email do
+            expose :third
+          end
+          subject.entity_class.exposures.size.should == 3
+        end
+
+        context 'instance' do
+          let(:instance){ subject.new }
+
+          describe '#entity' do
+            it 'should be an instance of the entity class' do
+              instance.entity.should be_kind_of(subject.entity_class)
+            end
+
+            it 'should have an object of itself' do
+              instance.entity.object.should == instance
+            end
+          end
+        end
+      end
+    end
   end
 end
diff --git a/spec/grape/validations/coerce_spec.rb b/spec/grape/validations/coerce_spec.rb
index f7ba16bf0a..f218d0b230 100644
--- a/spec/grape/validations/coerce_spec.rb
+++ b/spec/grape/validations/coerce_spec.rb
@@ -111,6 +111,19 @@ class User
         last_response.status.should == 201
         last_response.body.should == File.basename(__FILE__).to_s
       end
+
+      it 'Nests integers' do
+        subject.params do
+          group :integers do
+            requires :int, :coerce => Integer
+          end
+        end
+        subject.get '/int' do params[:integers][:int].class; end
+
+        get '/int', { :integers => { :int => "45" } }
+        last_response.status.should == 200
+        last_response.body.should == 'Fixnum'
+      end
     end
   end
 end
diff --git a/spec/grape/validations/presence_spec.rb b/spec/grape/validations/presence_spec.rb
index 2dd5f54e8a..6680a817e9 100644
--- a/spec/grape/validations/presence_spec.rb
+++ b/spec/grape/validations/presence_spec.rb
@@ -6,7 +6,13 @@ module ValidationsSpec
     module PresenceValidatorSpec
       class API < Grape::API
         default_format :json
-        
+
+        resource :bacons do
+          get do
+            "All the bacon"
+          end
+        end
+
         params do
           requires :id, :regexp => /^[0-9]+$/
         end
@@ -20,6 +26,29 @@ class API < Grape::API
         get do
           "Hello"
         end
+
+        params do
+          group :user do
+            requires :first_name, :last_name
+          end
+        end
+        get '/nested' do
+          "Nested"
+        end
+
+        params do
+          group :admin do
+            requires :admin_name
+            group :super do
+              group :user do
+                requires :first_name, :last_name
+              end
+            end
+          end
+        end
+        get '/nested_triple' do
+          "Nested triple"
+        end
       end
     end
   end
@@ -27,6 +56,12 @@ class API < Grape::API
   def app
     ValidationsSpec::PresenceValidatorSpec::API
   end
+
+  it "does not validate for any params" do
+    get("/bacons")
+    last_response.status.should == 200
+    last_response.body.should == "All the bacon"
+  end
   
   it 'validates id' do
     post('/')
@@ -55,5 +90,49 @@ def app
     last_response.status.should == 200
     last_response.body.should == "Hello"
   end
-  
+
+  it 'validates nested parameters' do
+    get('/nested')
+    last_response.status.should == 400
+    last_response.body.should == "missing parameter: first_name"
+
+    get('/nested', :user => {:first_name => "Billy"})
+    last_response.status.should == 400
+    last_response.body.should == "missing parameter: last_name"
+
+    get('/nested', :user => {:first_name => "Billy", :last_name => "Bob"})
+    last_response.status.should == 200
+    last_response.body.should == "Nested"
+  end
+
+  it 'validates triple nested parameters' do
+    get('/nested_triple')
+    last_response.status.should == 400
+    last_response.body.should == "missing parameter: admin_name"
+
+    get('/nested_triple', :user => {:first_name => "Billy"})
+    last_response.status.should == 400
+    last_response.body.should == "missing parameter: admin_name"
+
+    get('/nested_triple', :admin => {:super => {:first_name => "Billy"}})
+    last_response.status.should == 400
+    last_response.body.should == "missing parameter: admin_name"
+
+    get('/nested_triple', :super => {:user => {:first_name => "Billy", :last_name => "Bob"}})
+    last_response.status.should == 400
+    last_response.body.should == "missing parameter: admin_name"
+
+    get('/nested_triple', :admin => {:super => {:user => {:first_name => "Billy"}}})
+    last_response.status.should == 400
+    last_response.body.should == "missing parameter: admin_name"
+
+    get('/nested_triple', :admin => { :admin_name => 'admin', :super => {:user => {:first_name => "Billy"}}})
+    last_response.status.should == 400
+    last_response.body.should == "missing parameter: last_name"
+
+    get('/nested_triple', :admin => { :admin_name => 'admin', :super => {:user => {:first_name => "Billy", :last_name => "Bob"}}})
+    last_response.status.should == 200
+    last_response.body.should == "Nested triple"
+  end
+
 end