Most virtual environments are sterile places where the objects rarely interact with each other, and the user moves through the space as if most of the objects weren't there. Interesting virtual environments require a high level of user interaction. The user must be able to interact with the objects in the environment, and there must be interesting activities occurring in the environment. Providing this level of interaction is a major challenge to both the virtual reality and animation research communities, and forms a fertile research area. This paper identifies some of the major issues in providing interesting behaviors for virtual environments. Some of these issues are illustrated by the problems we encountered when producing a virtual environment for skiing. This paper also outlines an approach to solving some of the problems with behaviors for virtual environments.