This study was conducted to explore that phase of coalition bargaining in which cooperative motivation is dominant. Subjects were 198 male undergraduate students divided into 66 groups of three members each. Each subject was confronted with the requirement of forming a coalition with another member of the triad. To manipulate the strength of cooperative motivation, the degree of importance for succeeding in forming a coalition and the level of anxiety associated with losing a coalition were varied. Each subject was asked to bargain in such a way as to maximize his share of the reward by forming a coalition with another member of the triad. The results may be summarized as follows: (1) as importance for succeeding in forming a coalition and anxiety associated with losing a coalition increased, subjects' motivation became more cooperative in nature; (2) reinforcing cooperative motivation increased the probability that subjects would make concessions in bargaining; and, (3) making concessions was extremely effective as a strategy for forming coalitions. However, the magnitude of concessions was not always in proportion to the strength of cooperative motivation. It was suggested, in summary, that further research is necessary to delineate the factors which facilitate or constrain a person's willingness to make concessions in such situations.