1. A computer program product comprising one or more computer-readable storage media having thereon computer-executable instructions that, when executed by one or more processors of the computing system, cause the computing system to perform the following: an act of accessing one or more claims having an expression regarding a requesting entity; an act of evaluating the expression of at least one of each of the one or more claims; an act of assigning the requesting entity to one or more identities using the evaluation of the expression of the claim; an act of identifying an access policy corresponding to at least one of the one or more identities, the access policy specifying an action and a permission status corresponding to one or more resources belonging to a relying party; for each of at least one of the one or more corresponding resources, an act of identifying role information corresponding to one or more roles that, if held by the requesting entity, would cause a provider of the corresponding resource to enforce the permission status for the action should the requesting entity request to perform the action on the corresponding resource; and an act of constructing a security token that indicates the role information for each of the at least one of the corresponding one or more resources.