Previous research on teams has found that agreeableness is one of the strongest personality predictors of team performance, yet one of the weakest personality predictors of individual-level job performance. In this study, we examined why teams with more agreeable members perform better. Data were collected across 4 months at 5 points in time from 107 project teams. We found that agreeableness affects performance through communication and cohesion and that communication precedes cohesion in time. Furthermore, we found that virtualness moderated the relationships between agreeableness and communication, as well as between agreeableness and team performance, such that teams only benefitted from high levels of agreeableness when interacting face-to-face.