We want to build programming systems that can converse with their users to build computer programs. Such systems will enable users without programming expertise to write programs using natural language. The text-based, virtual-world environments called the MOO (multi-user, object-oriented Dungeons and Dragons) allow their users to build objects and give them simple, interactive, text-based behaviors. These behaviors allow other participants in the environment to interact with those objects by invoking actions and receiving text messages. Through our natural-language dialogue system, the beginning programmer will be able to describe objects and the messages in MOO environments.