A distributed network identity is provided. An identity provider stores a portion of a user's personal information. A service provider accesses user information from one or more identity providers. System entities such as identity providers and service providers can be linked to enable information sharing and aggregation. User policies and privacy preferences are provided to control how information is shared. A single sign-on architecture is provided where an identity provider is used to facilitate cross-domain authentication and to enhance user convenience. Service delegation features are also provided.