We describe a hybrid expert diagnosis-advisory system developed for small and medium enterprises. The Performance, Development, Growth (PDG) system is completely implemented and fully operational, and has been successfully used on real-world data from SMEs for several years. Although our system contains a great deal of the domain knowledge and expertise that is a hallmark of AI systems, it was not designed using the symbolic techniques traditionally used to implement such systems. We explain why this is so and discuss how the PDG system relates to expert systems, decision support systems, and general applications in AI. We also present an experimental evaluation of the system and identify developments currently under way and our plans for the future.