This chapter postulates that the problem solving process in many domains involves identifying the class of problem on hand, identifying an appropriate solution, and recognising opportunities for its reuse. A solution is suggested that builds up knowledge of a given domain by recording observations, diagnoses and actions in a ‘3Cs form’ of Cases, Classifications and Conclusions. This solution allows knowledge workers in any domain where heuristics are relied on to form classifications, and then apply generalised conclusions on the basis of the given classification, to collaboratively refine and expand a topic by consistently asking users to confirm, add to, or refine the presented knowledge in the context of the current case being classified. The solution is presented in the context of the Corporate Call Centre and is a significant extension of the Multiple Classification Ripple Down Rules algorithm. A 3Cs Logic Wiki is presented that takes the best features of current collaborative knowledge exchange mechanisms, and captures a logic structure on top of that which provides for rapid indexing of acquired knowledge.