A set of scenarios is a useful way to capture many aspects of the requirements of a system. Use Case Maps are a method for scenario capture which is good for describing multiple scenarios, including scenario interactions, for developingan architecture, and for analysing architectural alternatives. However, once a component architecture is determined, Message Sequence Charts are better for developing and presentingthe details of interactions, and provide access to well-developed methodologies and tools for analysis and synthesis. This paper considers what must be specified in UCM scenarios and the architecture to make it possible to derive MSCs automatically, and it describes our experience in executingthese transformations within a prototype tool, the UCM Navigator.