Multi-factor authentication for managed directories

A user transmits a request to an authentication service to access a managed directory. The request may include a first set of credentials usable by a managed directory service to authenticate the user. As a result of the first set of credentials being valid, the authentication service may prompt the user to provide a multi-factor authentication code, which may be used by an authentication server to further authenticate the user and enable the user to access the managed directory. The authentication service subsequently provides the multi-factor authentication code to the authentication server for validation. If the multi-factor authentication code is valid, the authentication service may enable the user to access the managed directory through an encrypted communications session.