Data Flow Analysis as expressed by Monotone Frameworks is often associated with classical imperative programming languages and has played a crucial role in the efficient implementation of these languages. Robin Milner's Calculus of Communicating Systems, CCS, is concerned with modelling concurrent systems and has mainly been analysed using types and control flow analysis. In the present paper we present an instance of a Monotone Framework for more precisely approximating the control structure of processes expressed in CCS.