Recent advances in logics for reasoning about resources provide a new approach to compositional reasoning in interacting systems. We present a calculus of resources and processes, based on a development of Milner's synchronous calculus of communication systems, SCCS, that uses an explicit model of resource. Our calculus models the co- evolution of resources and processes with synchronization constrained by the availability of resources. We provide a logical characterization, analogous to Hennessy-Milner logic's characterization of bisimulation in CCS, of bisimulation between resource processes which is compositional in the concurrent and local structure of systems. Notes: David Pym visiting from University of Bath 28 Pages