Military tasks often require the coordinated effort of a team of operators for successful execution. In tactical decision making situations, team members must gather, integrate and communicate crucial information in support of decisions where an incorrect response can have catastrophic consequences. Therefore, a viable goal of training for tactical decision making teams must be to improve the quality of teamwork and team coordination. It has been argued recently that the nature of teamwork and coordination behavior can be understood in terms of mental model theory. The notion of "mental models" has been invoked as an explanatory mechanism by those studying skilled performance and system control for a number of years. With respect to training, several researchers have suggested that the goal of instruction should be to foster accurate mental representations of the task. It is contended in this paper that the mental model construct may be particularly useful in developing team training strategies and understanding the nature of teamwork. Specifically, the ability of teams to coordinate activity and adapt to task demands in absence of overt communication opportunities may be hypothesized to be a result of shared mental models of the task and team among members. A rationale for adopting the shared mental model hypothesis is presented, along with the implications of such a position for training design.