The present invention authenticates a user for multiple resources distributed across multiple domains through the performance of a single authentication. User access requests for a protected resource in a first domain are received and redirected to a second domain. User authentication is performed at the second domain. In one embodiment, the system transmits an authentication cookie for the second domain to the user after authentication at the second domain. In another embodiment, the system further redirects subsequent resource requests for resources in the first domain or a third domain to the second domain. The second domain confirms the user's authentication for applicable portions of the first, second, and third domains using the cookie.