This thesis presents an approach to rapid prototyping called behavioral demonstration that allows a system to be demonstrated at any point during its development. This approach is based on the operational specification approach to software design and uses a new, automation based life-cycle paradigm. This work describes a tool that supports behavioral demonstration called the behavioral demonstrator that collects and manages information typically lost during software system design but critically needed during maintenance. The tool also supports project-personnel management and software complexity and cost estimation. The research takes place in the context of a dialogue management system and software design methodology that features the logical and physical separation of the input, processing, and output components of interactive systems. / M.S.