Is “be yourself” always the best advice? We suggest that interpersonal consequences of behaving authentically depend on the extent to which individuals identify with the social environment where they behave authentically. Bridging the research on authenticity, social identity, and conflict, we propose that for high identifiers, authentic behavior reveals how similar they are to others, thereby reducing dyadic relationship conflict. When social identification is low, behaving authentically increases the salience of how different the individual is from others, increasing relationship conflict. In a multi-source time-lag sample of professional work teams (Study 1), we found that authentic behavior indeed reduced relationship conflict and enhanced task performance for high identifiers, but had an inverse, detrimental effect for low identifiers. In a sample of student teams (Study 2), we only found an attenuating effect of authentic behavior on relationship conflict for high identifiers, and no effect for low identifiers. These results suggest that the advice “to be yourself” applies in educational contexts involving younger adults, but has to be prescribed with care in professional work contexts. Our findings emphasize the importance of social context for the consequences of authentic behavior, and call for more research on the contextual effects of authenticity.