A computer system is presented for facilitating user enrollment at service
providers, particularly with respect to storage and retrieval of user
attribute information within a federated environment at entities that
manage such information as a service. One domain can inform other domains
of identities of service providers that are to be associated with a user,
thereby enrolling information about the user at those domains. In
addition, an enrollment operation can be invoked by a first service
provider through a second service provider such that the user becomes
enrolled at a third service provider. During an enrollment operation,
information about multiple service providers may be associated with a
user, and these service providers may be prioritized. The user may be
provided an opportunity to reprioritize the service providers during the
enrollment operation so that the service providers are subsequently
contacted or used in a particular priority order.