A computing system comprising: one or more processors; and one or more computer-readable media having stored thereon computer-executable instructions that are structured such that, when executed by the one or more processors, cause the computing system to perform a method for automatically attempting selection of an identity provider to be used to authenticate users when the users request access to one or more network resources of a tenant over a network, the method comprising the following for each of a plurality of user requests to access: an act of receiving a user request to access a network resource; an act of identifying a tenant associated with the network resource; an act of identifying a username associated with the user; an act of initiating authentication of the user by performing an act of checking the username against a directory (240; 400) of the identified tenant, wherein if the act of checking the username against the directory results in finding an entry for the username in the directory of the identified tenant, the method includes an act of checking the entry for an identity provider corresponding to the username, wherein if the act of checking the entry for an identity provider results in finding an identity provider corresponding to the username, the method includes an act of causing the user to be directed to the found identity provider for authentication. one or more processors; and one or more computer-readable media having stored thereon computer-executable instructions that are structured such that, when executed by the one or more processors, cause the computing system to perform a method for automatically attempting selection of an identity provider to be used to authenticate users when the users request access to one or more network resources of a tenant over a network, the method comprising the following for each of a plurality of user requests to access: an act of receiving a user request to access a network resource; an act of identifying a tenant associated with the network resource; an act of identifying a username associated with the user; an act of initiating authentication of the user by performing an act of checking the username against a directory (240; 400) of the identified tenant, wherein if the act of checking the username against the directory results in finding an entry for the username in the directory of the identified tenant, the method includes an act of checking the entry for an identity provider corresponding to the username, wherein if the act of checking the entry for an identity provider results in finding an identity provider corresponding to the username, the method includes an act of causing the user to be directed to the found identity provider for authentication. an act of receiving a user request to access a network resource; an act of identifying a tenant associated with the network resource; an act of identifying a username associated with the user; an act of initiating authentication of the user by performing an act of checking the username against a directory (240; 400) of the identified tenant, wherein if the act of checking the username against the directory results in finding an entry for the username in the directory of the identified tenant, the method includes an act of checking the entry for an identity provider corresponding to the username, wherein if the act of checking the entry for an identity provider results in finding an identity provider corresponding to the username, the method includes an act of causing the user to be directed to the found identity provider for authentication.