diff --git a/lib/travis/api/v3.rb b/lib/travis/api/v3.rb
index 824f90bd..d2c19859 100644
--- a/lib/travis/api/v3.rb
+++ b/lib/travis/api/v3.rb
@@ -21,6 +21,7 @@ module Travis
       end
 
       extend self
+      load_dir("#{__dir__}/v3/extensions")
       load_dir("#{__dir__}/v3")
 
       ClientError        = Error        .create(status: 400)
diff --git a/lib/travis/api/v3/access_control/generic.rb b/lib/travis/api/v3/access_control/generic.rb
index 8c49dce9..fd68c26f 100644
--- a/lib/travis/api/v3/access_control/generic.rb
+++ b/lib/travis/api/v3/access_control/generic.rb
@@ -52,8 +52,17 @@ module Travis::API::V3
     private
 
     def dispatch(object, method = caller_locations.first.base_label)
-      method = object.class.name.underscore + ?_.freeze + method
+      method = method_for(object.class, method)
       send(method, object) if respond_to?(method, true)
     end
+
+    @@method_for_cache = Tool::ThreadLocal.new
+
+    def method_for(type, method)
+      @@method_for_cache[[type, method]] ||= begin
+        prefix = type.name.sub(/^Travis::API::V3::Models::/, ''.freeze).underscore
+        "#{prefix}_#{method}"
+      end
+    end
   end
 end
diff --git a/lib/travis/api/v3/extensions/belongs_to.rb b/lib/travis/api/v3/extensions/belongs_to.rb
new file mode 100644
index 00000000..dc0fcba3
--- /dev/null
+++ b/lib/travis/api/v3/extensions/belongs_to.rb
@@ -0,0 +1,32 @@
+module Travis::API::V3
+  module Extensions
+    module BelongsTo
+      module ClassMethods
+        def polymorfic_foreign_types
+          @polymorfic_foreign_types ||= []
+        end
+
+        def belongs_to(field, options = {})
+          polymorfic_foreign_types << (options[:foreign_type] || "#{field}_type") if options[:polymorphic]
+          super
+        end
+      end
+
+      def self.included(base)
+        base.extend(ClassMethods)
+        super
+      end
+
+      def [](key)
+        value   = super
+        value &&= "#{self.class.parent}::#{value}" if self.class.polymorfic_foreign_types.include?(key)
+        value
+      end
+
+      def []=(key, value)
+        value &&= value.sub("#{self.class.parent}::") if self.class.polymorfic_foreign_types.include?(key)
+        super(key, value)
+      end
+    end
+  end
+end
diff --git a/lib/travis/api/v3/model.rb b/lib/travis/api/v3/model.rb
new file mode 100644
index 00000000..90b26d1d
--- /dev/null
+++ b/lib/travis/api/v3/model.rb
@@ -0,0 +1,6 @@
+module Travis::API::V3
+  class Model < ActiveRecord::Base
+    include Extensions::BelongsTo
+    self.abstract_class = true
+  end
+end
diff --git a/lib/travis/api/v3/models.rb b/lib/travis/api/v3/models.rb
new file mode 100644
index 00000000..3504a13a
--- /dev/null
+++ b/lib/travis/api/v3/models.rb
@@ -0,0 +1,5 @@
+module Travis::API::V3
+  module Models
+    extend ConstantResolver
+  end
+end
diff --git a/lib/travis/api/v3/models/broadcast.rb b/lib/travis/api/v3/models/broadcast.rb
new file mode 100644
index 00000000..9c713d8e
--- /dev/null
+++ b/lib/travis/api/v3/models/broadcast.rb
@@ -0,0 +1,5 @@
+module Travis::API::V3
+  class Models::Broadcast < Model
+    belongs_to :recipient, polymorphic: true
+  end
+end
diff --git a/lib/travis/api/v3/models/build.rb b/lib/travis/api/v3/models/build.rb
new file mode 100644
index 00000000..9b7f766b
--- /dev/null
+++ b/lib/travis/api/v3/models/build.rb
@@ -0,0 +1,10 @@
+module Travis::API::V3
+  class Models::Build < Model
+    belongs_to :repository
+    belongs_to :commit
+    belongs_to :request
+    belongs_to :repository, autosave: true
+    belongs_to :owner, polymorphic: true
+    has_many   :jobs, as: :source, order: :id, dependent: :destroy
+  end
+end
diff --git a/lib/travis/api/v3/models/commit.rb b/lib/travis/api/v3/models/commit.rb
new file mode 100644
index 00000000..ac1add22
--- /dev/null
+++ b/lib/travis/api/v3/models/commit.rb
@@ -0,0 +1,6 @@
+module Travis::API::V3
+  class Models::Commit < Model
+    belongs_to :repository
+    has_one    :request
+  end
+end
diff --git a/lib/travis/api/v3/models/email.rb b/lib/travis/api/v3/models/email.rb
new file mode 100644
index 00000000..6fd9cd7e
--- /dev/null
+++ b/lib/travis/api/v3/models/email.rb
@@ -0,0 +1,5 @@
+module Travis::API::V3
+  class Models::Email < Model
+    belongs_to :user
+  end
+end
diff --git a/lib/travis/api/v3/models/job.rb b/lib/travis/api/v3/models/job.rb
new file mode 100644
index 00000000..2db5df10
--- /dev/null
+++ b/lib/travis/api/v3/models/job.rb
@@ -0,0 +1,10 @@
+module Travis::API::V3
+  class Models::Job < Model
+    has_one    :log, dependent: :destroy
+    belongs_to :repository
+    belongs_to :commit
+    belongs_to :build, autosave: true, foreign_key: 'source_id'
+    belongs_to :owner, polymorphic: true
+    serialize :config
+  end
+end
diff --git a/lib/travis/api/v3/models/log.rb b/lib/travis/api/v3/models/log.rb
new file mode 100644
index 00000000..d1c3219b
--- /dev/null
+++ b/lib/travis/api/v3/models/log.rb
@@ -0,0 +1,7 @@
+module Travis::API::V3
+  class Models::Log < Model
+    belongs_to :job
+    belongs_to :removed_by, class_name: 'User', foreign_key: :removed_by
+    has_many  :log_parts, dependent: :destroy
+  end
+end
diff --git a/lib/travis/api/v3/models/log_part.rb b/lib/travis/api/v3/models/log_part.rb
new file mode 100644
index 00000000..43fc7370
--- /dev/null
+++ b/lib/travis/api/v3/models/log_part.rb
@@ -0,0 +1,5 @@
+module Travis::API::V3
+  class Models::LogPart < Model
+    belongs_to :log
+  end
+end
diff --git a/lib/travis/api/v3/models/membership.rb b/lib/travis/api/v3/models/membership.rb
new file mode 100644
index 00000000..b32fe2ea
--- /dev/null
+++ b/lib/travis/api/v3/models/membership.rb
@@ -0,0 +1,6 @@
+module Travis::API::V3
+  class Models::Membership < Model
+    belongs_to :user
+    belongs_to :organization
+  end
+end
diff --git a/lib/travis/api/v3/models/organization.rb b/lib/travis/api/v3/models/organization.rb
new file mode 100644
index 00000000..e42e3364
--- /dev/null
+++ b/lib/travis/api/v3/models/organization.rb
@@ -0,0 +1,7 @@
+module Travis::API::V3
+  class Models::Organization < Model
+    has_many :memberships
+    has_many :users, through: :memberships
+    has_many :repositories, as: :owner
+  end
+end
diff --git a/lib/travis/api/v3/models/permission.rb b/lib/travis/api/v3/models/permission.rb
new file mode 100644
index 00000000..7c592903
--- /dev/null
+++ b/lib/travis/api/v3/models/permission.rb
@@ -0,0 +1,6 @@
+module Travis::API::V3
+  class Models::Permission < Model
+    belongs_to :user
+    belongs_to :repository
+  end
+end
diff --git a/lib/travis/api/v3/models/repository.rb b/lib/travis/api/v3/models/repository.rb
new file mode 100644
index 00000000..67aa37e8
--- /dev/null
+++ b/lib/travis/api/v3/models/repository.rb
@@ -0,0 +1,23 @@
+module Travis::API::V3
+  class Models::Repository < Model
+    has_many :commits,     dependent: :delete_all
+    has_many :requests,    dependent: :delete_all
+    has_many :builds,      dependent: :delete_all
+    has_many :permissions, dependent: :delete_all
+    has_many :users,       through:   :permissions
+
+    belongs_to :owner, polymorphic: true
+
+    has_one :last_build,
+      class_name: 'Travis::API::V3::Models::Build'.freeze,
+      order:      'id DESC'.freeze
+
+    def slug
+      @slug ||= "#{owner_name}/#{name}"
+    end
+
+    def last_build_on(branch)
+      builds.order('id DESC'.freeze).where(branch: branch, event_type: 'push'.freeze).first
+    end
+  end
+end
diff --git a/lib/travis/api/v3/models/request.rb b/lib/travis/api/v3/models/request.rb
new file mode 100644
index 00000000..fd1387a8
--- /dev/null
+++ b/lib/travis/api/v3/models/request.rb
@@ -0,0 +1,10 @@
+module Travis::API::V3
+  class Models::Request < Model
+    belongs_to :commit
+    belongs_to :repository
+    belongs_to :owner, polymorphic: true
+    has_many   :builds
+    serialize  :config
+    serialize  :payload
+  end
+end
diff --git a/lib/travis/api/v3/models/ssl_key.rb b/lib/travis/api/v3/models/ssl_key.rb
new file mode 100644
index 00000000..eb45758c
--- /dev/null
+++ b/lib/travis/api/v3/models/ssl_key.rb
@@ -0,0 +1,5 @@
+module Travis::API::V3
+  class Models::SSLKey < Model
+    belongs_to :repository
+  end
+end
diff --git a/lib/travis/api/v3/models/user.rb b/lib/travis/api/v3/models/user.rb
new file mode 100644
index 00000000..73136efd
--- /dev/null
+++ b/lib/travis/api/v3/models/user.rb
@@ -0,0 +1,5 @@
+module Travis::API::V3
+  class Models::User < Model
+    has_many :emails
+  end
+end
diff --git a/lib/travis/api/v3/queries/build.rb b/lib/travis/api/v3/queries/build.rb
index 7d1594a2..f227761a 100644
--- a/lib/travis/api/v3/queries/build.rb
+++ b/lib/travis/api/v3/queries/build.rb
@@ -3,7 +3,7 @@ module Travis::API::V3
     params :id
 
     def find
-      return ::Build.find_by_id(id) if id
+      return Models::Build.find_by_id(id) if id
       raise WrongParams
     end
   end
diff --git a/lib/travis/api/v3/queries/organization.rb b/lib/travis/api/v3/queries/organization.rb
index a88f412c..ae971d7a 100644
--- a/lib/travis/api/v3/queries/organization.rb
+++ b/lib/travis/api/v3/queries/organization.rb
@@ -3,7 +3,7 @@ module Travis::API::V3
     params :id
 
     def find
-      return ::Organization.find_by_id(id) if id
+      return Models::Organization.find_by_id(id) if id
       raise WrongParams
     end
   end
diff --git a/lib/travis/api/v3/queries/organizations.rb b/lib/travis/api/v3/queries/organizations.rb
index 42d84d4f..faa3f68b 100644
--- a/lib/travis/api/v3/queries/organizations.rb
+++ b/lib/travis/api/v3/queries/organizations.rb
@@ -1,7 +1,7 @@
 module Travis::API::V3
   class Queries::Organizations < Query
     def for_member(user)
-      ::Organization.joins(:users).where(users: user_condition(user))
+      Models::Organization.joins(:users).where(users: user_condition(user))
     end
   end
 end
diff --git a/lib/travis/api/v3/queries/repositories.rb b/lib/travis/api/v3/queries/repositories.rb
index 1f4c0c22..04834ccd 100644
--- a/lib/travis/api/v3/queries/repositories.rb
+++ b/lib/travis/api/v3/queries/repositories.rb
@@ -8,7 +8,7 @@ module Travis::API::V3
 
     def all
       @all ||= begin
-        all = ::Repository
+        all = Models::Repository
         all = all.where(active:  bool(active))  unless active.nil?
         all = all.where(private: bool(private)) unless private.nil?
         all
diff --git a/lib/travis/api/v3/queries/repository.rb b/lib/travis/api/v3/queries/repository.rb
index fa1e6d35..6542c7b9 100644
--- a/lib/travis/api/v3/queries/repository.rb
+++ b/lib/travis/api/v3/queries/repository.rb
@@ -3,7 +3,7 @@ module Travis::API::V3
     params :id
 
     def find
-      return ::Repository.find_by_id(id) if id
+      return Models::Repository.find_by_id(id) if id
       raise WrongParams
     end
   end
diff --git a/lib/travis/api/v3/renderer/model_renderer.rb b/lib/travis/api/v3/renderer/model_renderer.rb
index 0c508172..65de8be1 100644
--- a/lib/travis/api/v3/renderer/model_renderer.rb
+++ b/lib/travis/api/v3/renderer/model_renderer.rb
@@ -47,17 +47,17 @@ module Travis::API::V3
       result
     end
 
-    def render_model(model, type: model.class.name.to_sym, mode: :minimal, **options)
+    def render_model(model, type: model.class.name[/[^:]+$/].to_sym, mode: :minimal, **options)
       Renderer[type].render(model, mode, script_name: script_name, **options)
     end
 
     def render_value(value)
       case value
-      when Hash          then value.map { |k, v| [k, render_value(v)] }.to_h
-      when Array         then value.map { |v   | render_value(v)      }
-      when *PRIMITIVE    then value
-      when Time          then value.strftime('%Y-%m-%dT%H:%M:%SZ')
-      when Travis::Model then render_model(value)
+      when Hash        then value.map { |k, v| [k, render_value(v)] }.to_h
+      when Array       then value.map { |v   | render_value(v)      }
+      when *PRIMITIVE  then value
+      when Time        then value.strftime('%Y-%m-%dT%H:%M:%SZ')
+      when Model       then render_model(value)
       else raise ArgumentError, 'cannot render %p (%p)' % [value.class, value]
       end
     end