This research focused on the contribution to group effectiveness of one aspect of the leader-men relationship. The general hypothesis is that the more a leader satisfies the needs of his men, the more effective group performance. Observations of infantry rifle squads during field problems suggested, for example, that a leader's stature and tone of voice bore little, if any, relationship to his control of the squad or to the squad's performance. The significant variables appeared to be less obvious and more subtle. On the basis of discussions with noncommissioned officers and with one particular squad leader (SL) who had just been tested on a field problem the idea was developed of reciprocality of indulgences and its relationship to squad effectiveness. In a series of four field research studies involving 272 Army infantry rifle squads and Air Force crews several specific hypotheses were tested. These hypotheses were derived from the theory of the reciprocality of indulgences. The theory indicates that the more a leader satisfies the needs of his men the harder they will work for him on a field problem and, therefore, the better the group will perform. Through the use of the interpersonal theory of the reciprocality of indulgences it was possible to account for some of the variance in the effectiveness of group behavior. Laboratory research is required to test further the conclusions drawn and other field and laboratory studies can explore the effects on group effectiveness of interpersonal relationships similar to the reciprocality of indulgences.