This paper describes the design and implementation of the Fully Immersive Team Training (FITT) research system. FITT was developed to support research on the use of distributed virtual environments (VEs) for team training. A generic search mission was created and modeled after decision-making and procedural tasks used by military and civilian small teams in conducting missions in emergency situations. The hardware and software functional requirements for the development of FITT were defined by the characteristics of the mission environment to be simulated, the team members' actions and interactions necessary to complete the mission, and instructional features and interventions relevant to training research. These requirements included locomotion, object manipulation and aiming, communication among participants, design of avatars for participants and computer-generated forces, data capture and playback, and a host of networking issues. A brief description of the first experiment conducted with FITT is presented as an example of how the system will be used in VE training research.