diff --git a/README.md b/README.md
index b7ac87c..449a49e 100644
--- a/README.md
+++ b/README.md
@@ -135,10 +135,18 @@ In the config directory, create a YAML file (`attribute-map.yml`) that maps SAML
 ```yaml
   # attribute-map.yml
 
-  "urn:mace:dir:attribute-def:uid": "user_name"
-  "urn:mace:dir:attribute-def:email": "email"
-  "urn:mace:dir:attribute-def:name": "last_name"
-  "urn:mace:dir:attribute-def:givenName": "name"
+  "urn:mace:dir:attribute-def:email":
+    "resource_key": "email"
+    "attribute_type": "single"
+  "urn:mace:dir:attribute-def:name":
+    "resource_key": "last_name"
+    "attribute_type": "single"
+  "urn:mace:dir:attribute-def:name":
+    "resource_key": "first_name"
+    "attribute_type": "single"
+  "urn:mace:dir:attribute-def:roles":
+    "resource_key": "roles"
+    "attribute_type": "multi"
 ```
 
 The attribute mappings are very dependent on the way the IdP encodes the attributes.
diff --git a/lib/devise_saml_authenticatable/saml_mapped_attributes.rb b/lib/devise_saml_authenticatable/saml_mapped_attributes.rb
index a1ebd95..07cd92e 100644
--- a/lib/devise_saml_authenticatable/saml_mapped_attributes.rb
+++ b/lib/devise_saml_authenticatable/saml_mapped_attributes.rb
@@ -10,20 +10,20 @@ def saml_attribute_keys
     end
 
     def resource_keys
-      @attribute_map.values
+      @attribute_map.values.map { |h| h["resource_key"] }
     end
 
     def value_by_resource_key(key)
       str_key = String(key)
 
       # Find all of the SAML attributes that map to the resource key
-      attribute_map_for_key = @attribute_map.select { |_, resource_key| String(resource_key) == str_key }
+      attribute_map_for_key = @attribute_map.select { |_, config| String(config["resource_key"]) == str_key }
 
       saml_value = nil
 
       # Find the first non-nil value
-      attribute_map_for_key.each_key do |saml_key|
-        saml_value = value_by_saml_attribute_key(saml_key)
+      attribute_map_for_key.each_pair do |saml_key, config|
+        saml_value = value_by_saml_attribute_key(saml_key, config)
 
         break unless saml_value.nil?
       end
@@ -31,8 +31,8 @@ def value_by_resource_key(key)
       saml_value
     end
 
-    def value_by_saml_attribute_key(key)
-      @attributes[String(key)]
+    def value_by_saml_attribute_key(key, config)
+      @attributes.send(config["attribute_type"], String(key))
     end
   end
 end