1. A method comprising: by one or more computing devices of a social-networking system, receiving a request from a third-party system to create a social-networking account for a user external to the third-party system; by the one or more computing devices, receiving user-related information from the third-party system; by the one or more computing devices, generating the social-networking account for the user, the social-networking account comprising a user profile and a user node in a social graph comprising a plurality of nodes and a plurality of edges connecting the nodes; by the one or more computing devices, providing social-networking account data to the third-party system; and determining, for each of one or more contacts of the user, that a user node exists in the social graph for the contact; and generating in the social graph an edge connecting the user node for the contact and the user node for the user.