Continuous user authentication includes receiving authentication event information including (1) transaction information describing authentication transactions, the transaction information received from authentication providers and including identification of users and instances of authentication of the users by the authentication providers, and (2) user identification and activity information describing presence and state (e.g. location) of the users, this information received from (a) mobile sensing devices in physical proximity of users independent of user location, and (b) stationary sensing devices at fixed locations of the users. The authentication event information is stored in an authentication event database and is provided to the authentication providers in a continual manner to enable the authentication providers to (a) establish new authentications of the users for accessing services of the computing system, and (b) maintain and revoke previously established authentications of the users based on the authentication event information and authentication policies.