This paper gives an overview of the INCAS (INCremental Architecture for distributed Systems) multicomputer project, which aims at the development of a comprehensive methodology for the design and implementation of locally distributed systems. A structuring concept for distributed operating systems has been developed and integrated into the system implementation language LADY. The concurrent high-level programming language CSSA, based on the actor model, has been designed for the implementation of distributed applications. A substantial effort in the INCAS project is directed towards the development of a distributed test methodology. An experimental system has been implemented on a network of ten MC68000 microcomputers. Preliminary experience with the methodology has been gained from a small number of prototype applications.