1. A computer implemented method for providing access to communities of users in an online social network, the method comprising: receiving, at a server, a user identity (ID) from a computing device; identifying the user ID as one of a plurality of first user identities (IDs) of first users belonging to a first community maintained on behalf of a first organization by a social networking system; providing, to the computing device, access to the first community responsive to identifying the user ID as one of the first user IDs; receiving, from the computing device, a request to access a second community maintained on behalf of a second organization; identifying the user ID as one of a plurality of second user IDs of second users belonging to the second community; and providing, to the computing device, access to the second community responsive to identifying the user ID as one of the second user IDs.