Abstract: Generalized Role-Based Access Control (GRBAC) is a new paradigm for creating and maintaining rich access control policies. GRBAC leverages and extends the power of traditional Role-Based Access Control (RBAC) by incorporating subject roles, object roles and environment roles into access control decisions. Subject roles are like traditional RBAC roles: they abstract the security-relevant characteristics of subjects into categories that can be used in defining a security policy. Similarly, object roles abstract the various properties of objects, such as object type (e.g., text, JPEG, executable) or sensitivity level (e.g., classified, top secret) into categories. Environment roles capture environmental information, such as time of day or system load, so it can be used to mediate access control. Together, these three types of roles offer flexibility and expressive power, as well as a degree of usability not found in current access control models.