Abstract. Communities of cooperating problem solvers have recently begun to emerge as a paradigm for overcoming the complexity of building large software systems in the area of process control. Each agent is capable of solving some problems by itself, but its power can be extended by sharing information and tasks with others. Also, more importantly, the community as a whole exhibits some desirable problem solving characteristics (eg graceful degradation of performance, robustness, etc.) as well as offering the opportunity of connecting and integrating existing problem solvers. GRATE is a general purpose cooperation environment which enables groups of interacting problem solvers to be built for the domain of industrial control. It has been applied to two real-world problems in this area: electricity transport management and diagnosis in a particle accelerator beam controller. We reflect upon GRATE?s functional architecture, its underlying principles and the insights gained during this process.