The aim of this study was to investigate whether or not achievement behaviors were promoted if that behavior was also expected to be beneficial to friends. We used a viguette involving a part-time job situation. Participants were 106 university students. Participants who were instructed that any overtime they worked would help their friends' jobs worked longer than those who did not receive this instruction. In addition, we found work rate was related to specific personal traits. Work rate was positively correlated with sensitivity to rejection, and negatively correlated with individual-oriented motivation. These results suggest that expecting some benefit to friends increased achievement behaviors, although the amount of increase differed depending on personal traits.