diff --git a/authenticate.go b/authenticate.go
index 09ee36f..4d3254f 100644
--- a/authenticate.go
+++ b/authenticate.go
@@ -22,11 +22,58 @@
 	Password string `json:"password"`
 }
 
-type ProviderAccess interface {
-	// ...
+// Access encapsulates the API token and its relevant fields, as well as the
+// services catalog that Identity API returns once authenticated.  You'll probably
+// rarely use this record directly, unless you intend on marshalling or unmarshalling
+// Identity API JSON records yourself.
+type Access struct {
+	Token          Token
+	ServiceCatalog []CatalogEntry
+	User           User
 }
 
-func (c *Context) Authenticate(provider string, options AuthOptions) (ProviderAccess, error) {
+// Token encapsulates an authentication token and when it expires.  It also includes
+// tenant information if available.
+type Token struct {
+	Id, Expires string
+	Tenant      Tenant
+}
+
+// Tenant encapsulates tenant authentication information.  If, after authentication,
+// no tenant information is supplied, both Id and Name will be "".
+type Tenant struct {
+	Id, Name string
+}
+
+// User encapsulates the user credentials, and provides visibility in what
+// the user can do through its role assignments.
+type User struct {
+	Id, Name          string
+	XRaxDefaultRegion string `json:"RAX-AUTH:defaultRegion"`
+	Roles             []Role
+}
+
+// Role encapsulates a permission that a user can rely on.
+type Role struct {
+	Description, Id, Name string
+}
+
+// CatalogEntry encapsulates a service catalog record.
+type CatalogEntry struct {
+	Name, Type string
+	Endpoints  []EntryEndpoint
+}
+
+// EntryEndpoint encapsulates how to get to the API of some service.
+type EntryEndpoint struct {
+	Region, TenantId                    string
+	PublicURL, InternalURL              string
+	VersionId, VersionInfo, VersionList string
+}
+
+func (c *Context) Authenticate(provider string, options AuthOptions) (*Access, error) {
+	var access *Access
+
 	p, err := c.ProviderByName(provider)
 	if err != nil {
 		return nil, err
@@ -46,6 +93,11 @@
 				TenantId: options.TenantId,
 			},
 		},
+		Results: &struct{
+			Access **Access `json:"access"`
+		}{
+			&access,
+		},
 	})
-	return nil, err
+	return access, err
 }