Although the differential treatment of team members by their leader is at the heart of Leader– Member Exchange (LMX) theory empirical studies exploring the role of within-team LMX differentiation in relation to team outcomes are still relatively scarce. This study among 269 Dutch secondary school teachers from 33 different teams tested the hypotheses that the relationship between LMX differentiation and team commitment and team performance is moderated by LMX-quality median. Moreover we hypothesized that team members' perceived dissimilarity regarding work values and orientations would be positively related to withinteam LMX differentiation. Teachers completed questionnaires on LMX-quality dissimilarity and team commitment whereas team performance was rated by school principals. Results indeed showed that LMX differentiation is positively related to both outcome variables in teams with a low LMX-quality median only. As expected more perceived dissimilarity between team members was related to more within-team variability in LMX-scores. These results contribute to knowledge on hypothetical antecedents and consequences of LMX differentiation at the team level.