Diversity faultlines can have a detrimental impact on team performance. To test whether this impact depends on leaders’ and members’ pro-diversity beliefs, we examined 41 leaders and 219 members of teams working for the German Ministry of Foreign Affairs. Findings indicated that the negative impact of diversity faultlines on team performance was weakest when leaders and members held strong pro-diversity beliefs. However, we did not find support for the assumed two-way interactions between faultline strength and leaders’ or members’ pro-diversity beliefs or the mediating effect of Leader-Member Exchange. Our results highlight the joint impact of leaders’ and members’ pro-diversity beliefs for attenuating the negative consequences of diversity faultlines on team performance.