Expectation states theory, role congruity theory, and the biosocial model, respectively, predict that perceptions of competence, agency and communality, and physical dominance explain the effects of nonverbal communication on social influence. This study contrasts these mechanisms by using voice pitch variation as a nonverbal signal in mixed-sex dyads. Thirty-seven pairs of male and female participants were recorded discussing a controversial topic under conditions where either their gender or a shared identity as college students was salient. Consistent with expectation states theory, men who varied their pitch more during discussion were perceived as more competent and influential by their female interlocutors, but only when gender was salient. In the same condition, male and female participants’ pitch variation negatively predicted their perceptions of their discussion partner’s influence, suggesting that nonverbal communication constitutes and reflects competition over status. Our findings favor expectation states theory over role congruity theory and the biosocial model.