LA is a formal Logic of Argument which was originally developed as a flexible foundation for knowledge-level decision models, and to facilitate explanation and user-interface design. The logic has a clear semantics and is embodied in the PROforma language, a simple but effective representation for modeling decisions, plans and software agents. ASPIC is an EU funded project1 that aims to develop a general model for argumentation services including a consensus semantics and interchange format for argumentation in inference, decision-making, dialogue and learning. ASPIC is also providing an opportunity to extend PROforma to support multi-agent services. This is being used to implement a wide range of services in multidisciplinary cancer care.