Avatars, representations of people in virtual environments, are subject to human control. However, for most applications, it is impractical for a person to directly control each joint in a complex avatar. Rather, people must be allowed to specify complex behaviours with simple instructions and the avatar permitted to select the correct movements in sequence to execute the instruction. This requires a variety of technologies that are currently available. Human behaviour must be captured and stored it so that it can be retrieved at a later time for use by the avatar. This has been done successfully with a variety of haptic interfaces, with visual observation of human head movements, and with verbal behaviour in natural language applications. The behaviour must be broken into atomic actions that can be sequenced with a regular grammar, and an appropriate grammar developed. Finally, a user interface must be developed so that a person can deliver instructions to the avatar.