This study was a part of the program of cooperative research on team development and maturation involving the Center for Applied Psychology Studies of Old Dominion University and the Naval Training Systems Center, Orlando, Florida. In an effort to understand the specific behavioral components comprising teamwork, 11 Combat Information Center teams in an Anti-Submarine Warfare School, ranked according to an independent final exam score, were observed over a week training period. Team instructors served as the source of critical behavior data that were collected and analyzed. Results of the behavioral analysis indicate that teamwork is behaviorally complex and evolves over time; that teamwork skills contribute to the relative success of teams; and that top-ranked teams display certain behavioral tendencies distinct from the lowest-ranked teams. A sampling of the lessons learned from this research and recommendations for interventions to improve team performance and training are presented and discussed.