diff --git a/lib/fog/aws/parsers/sts/assume_role.rb b/lib/fog/aws/parsers/sts/assume_role.rb
new file mode 100644
index 000000000..2c28fce2c
--- /dev/null
+++ b/lib/fog/aws/parsers/sts/assume_role.rb
@@ -0,0 +1,30 @@
+module Fog
+  module Parsers
+    module AWS
+      module STS
+
+        class AssumeRole < Fog::Parsers::Base
+
+          def reset
+            @response = {}
+          end
+
+          def end_element(name)
+            case name
+            when 'SessionToken', 'SecretAccessKey', 'Expiration', 'AccessKeyId'
+              @response[name] = @value.strip
+            when 'Arn', 'AssumedRoleId'
+              @response[name] = @value.strip
+            when 'PackedPolicySize'
+              @response[name] = @value
+            when 'RequestId'
+              @response[name] = @value
+            end
+          end
+
+        end
+
+      end
+    end
+  end
+end
diff --git a/lib/fog/aws/requests/sts/assume_role.rb b/lib/fog/aws/requests/sts/assume_role.rb
new file mode 100644
index 000000000..afe393293
--- /dev/null
+++ b/lib/fog/aws/requests/sts/assume_role.rb
@@ -0,0 +1,46 @@
+module Fog
+  module AWS
+    class STS
+      class Real
+
+        require 'fog/aws/parsers/sts/assume_role'
+        
+        # Assume Role
+        #
+        # ==== Parameters
+        # * role_session_name<~String> - An identifier for the assumed role.
+        # * role_arn<~String> - The ARN of the role the caller is assuming.
+        # * external_id<~String> - An optional unique identifier required by the assuming role's trust identity.
+        # * policy<~String> - An optional JSON policy document
+        # * duration<~Integer> - Duration (of seconds) for the assumed role credentials to be valid (default 3600)
+        #
+        # ==== Returns
+        # * response<~Excon::Response>:
+        #   * body<~Hash>:
+        #     * 'Arn'<~String>: The ARN of the assumed role/user
+        #     * 'AccessKeyId'<~String>: The AWS access key of the temporary credentials for the assumed role
+        #     * 'SecretAccessKey'<~String>: The AWS secret key of the temporary credentials for the assumed role
+        #     * 'SessionToken'<~String>: The AWS session token of the temporary credentials for the assumed role
+        #     * 'Expiration'<~Time>: The expiration time of the temporary credentials for the assumed role
+        #
+        # ==== See Also
+        # http://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRole.html
+        #
+
+        def assume_role(role_session_name, role_arn, external_id=nil, policy=nil, duration=3600)
+          request({
+            'Action'          => 'AssumeRole',
+            'RoleSessionName' => role_session_name,
+            'RoleArn'         => role_arn,
+            'Policy'          => policy && Fog::JSON.encode(policy),
+            'DurationSeconds' => duration,
+            'ExternalId'      => external_id,
+            :idempotent       => true,
+            :parser           => Fog::Parsers::AWS::STS::AssumeRole.new
+          })
+        end
+        
+      end
+    end
+  end
+end
diff --git a/lib/fog/aws/sts.rb b/lib/fog/aws/sts.rb
index 8a8af8816..171fc14ac 100644
--- a/lib/fog/aws/sts.rb
+++ b/lib/fog/aws/sts.rb
@@ -3,16 +3,18 @@ require 'fog/aws'
 module Fog
   module AWS
     class STS < Fog::Service
+      extend Fog::AWS::CredentialFetcher::ServiceMethods
 
       class EntityAlreadyExists < Fog::AWS::STS::Error; end
       class ValidationError < Fog::AWS::STS::Error; end
 
       requires :aws_access_key_id, :aws_secret_access_key
-      recognizes :host, :path, :port, :scheme, :persistent
+      recognizes :host, :path, :port, :scheme, :persistent, :aws_session_token, :use_iam_profile, :aws_credentials_expire_at
 
       request_path 'fog/aws/requests/sts'
       request :get_federation_token
       request :get_session_token
+      request :assume_role
 
       class Mock
         def self.data
@@ -33,7 +35,8 @@ module Fog
         end
 
         def initialize(options={})
-          @aws_access_key_id = options[:aws_access_key_id]
+          @use_iam_profile = options[:use_iam_profile]
+          setup_credentials(options)
         end
 
         def data
@@ -43,10 +46,14 @@ module Fog
         def reset_data
           self.class.data.delete(@aws_access_key_id)
         end
+
+        def setup_credentials(options)
+          @aws_access_key_id = options[:aws_access_key_id]
+        end
       end
 
       class Real
-
+        include Fog::AWS::CredentialFetcher::ConnectionMethods
         # Initialize connection to STS
         #
         # ==== Notes
@@ -67,10 +74,10 @@ module Fog
         def initialize(options={})
           require 'fog/core/parser'
 
-          @aws_access_key_id      = options[:aws_access_key_id]
-          @aws_secret_access_key  = options[:aws_secret_access_key]
+          @use_iam_profile = options[:use_iam_profile]
+          setup_credentials(options)
           @connection_options     = options[:connection_options] || {}
-          @hmac       = Fog::HMAC.new('sha256', @aws_secret_access_key)
+
           @host       = options[:host]        || 'sts.amazonaws.com'
           @path       = options[:path]        || '/'
           @persistent = options[:persistent]  || false
@@ -85,6 +92,14 @@ module Fog
 
         private
 
+        def setup_credentials(options)
+          @aws_access_key_id      = options[:aws_access_key_id]
+          @aws_secret_access_key  = options[:aws_secret_access_key]
+          @aws_session_token      = options[:aws_session_token]
+          @aws_credentials_expire_at = options[:aws_credentials_expire_at]
+          @hmac = Fog::HMAC.new('sha256', @aws_secret_access_key)
+        end
+
         def request(params)
           idempotent  = params.delete(:idempotent)
           parser      = params.delete(:parser)
@@ -93,6 +108,7 @@ module Fog
             params,
             {
               :aws_access_key_id  => @aws_access_key_id,
+              :aws_session_token  => @aws_session_token,
               :hmac               => @hmac,
               :host               => @host,
               :path               => @path,
diff --git a/tests/aws/requests/sts/assume_role_tests.rb b/tests/aws/requests/sts/assume_role_tests.rb
new file mode 100644
index 000000000..3b8fa3e51
--- /dev/null
+++ b/tests/aws/requests/sts/assume_role_tests.rb
@@ -0,0 +1,19 @@
+Shindo.tests('AWS::STS | assume role', ['aws']) do
+
+	@policy = {"Statement" => [{"Effect" => "Allow", "Action" => "*", "Resource" => "*"}]}
+
+	@response_format = {
+		'SessionToken' => String,
+		'SecretAccessKey' => String,
+		'Expiration' => String,
+		'AccessKeyId' => String,
+		'Arn' => String,
+		'RequestId' => String
+	}
+	
+	tests("#assume_role('rolename', 'assumed_role_session', 'external_id', #{@policy.inspect}, 900)").formats(@response_format) do
+		pending if Fog.mocking?
+		Fog::AWS[:sts].assume_role("rolename","assumed_role_session","external_id", @policy, 900).body
+	end
+
+end