Composite systems are generally comprised of heterogeneous components whose specifications are developed by many development participants. The requirements of such systems are invariably elicited from multiple perspectives that overlap, complement, and contradict each other. Furthermore, these requirements are generally developed and specified using multiple methods and notations, respectively. It is therefore necessary to express and check the relationships between the resultant specification fragments. We deploy multiple ViewPoints that hold partial requirements specifications, described and developed using different representation schemes and development strategies. We discuss the notion of inter-ViewPoint communication in the context of this ViewPoints framework, and propose a general model for ViewPoint interaction and integration. We elaborate on some of the requirements for expressing and enacting inter-ViewPoint relationships-the vehicles for consistency checking and inconsistency management. Finally, though we use simple fragments of the requirements specification method CORE to illustrate various components of our work, we also outline a number of larger case studies that we have used to validate our framework. Our computer-based ViewPoints support environment, The Viewer, is also briefly described.<>