This paper¹ presents an architecture to meet the needs for authentication and authorization in Grid based component systems. While Grid Security Infrastructure (GSI) [1] is accepted as the standard for authentication on the Grid, distributed authorization is still an open problem being investigated by various groups [2],[3],[4]. Our design provides authentication and fine-grained authorization at the interface, method and parameter levels. We discuss the ways in which internal and external authorization services can be used in a component framework. The design is flexible to allow the use of various existing policy languages and authorization systems. Our prototype is based on XCAT, an implementation of the Common Component Architecture (CCA) specification.