A study was undertaken to improve the measurement of small team performance within the Army. A provisional taxonomy of team-level performance functions was field-validated; criteria and measures of the functions were developed; and their reliability was examined. The provisional taxonomy, used for observing Army field training exercises, was used to observe three types of Army teams: mortar squads, infantry squads, and assault ribbon bridge platoons. The taxonomy was then revised to include five functions: orientation; resource distribution (load balancing); timing (activity pacing); response coordination; and motivational functions. The first four of these functions were observed in a small-scale laboratory setting in which briefly trained subjects rated 15 videotaped segments of team activity. The ratings were generally reliable, although there was some acquiescence bias leading raters to rate functions as present when they were not. The experimental materials, including the Team Function Rating Scales, are appended. (GDC)