Integrating theorizing on situational strength and complementarity with control theory, we investigate the mediating processes that transmit peer control combination effects to team performance. We argue that two critical peer control mechanisms-norm strength and peer pressure-complement each other such that their joint impact on team members becomes stronger than the sum of their parts. In a multiple mediator model, we identify effort and trust as two distinct mediating processes that explain the relationship between peer control combinations and team performance. Multisource, multiwave data from 41 self-managing healthcare teams largely support our model. The pattern of mediation was more complex than we anticipated, revealing an indirect effect of peer controls on effort via trust. Together, our findings offer insight into how controls complement each other and the processes through which they do so.