Many complex organizational tasks are performed by networks of teams – multiteam systems. A critical challenge in multiteam systems is how to promote information exchange across teams. In three studies, we investigate how identity asymmetries, i.e., differences between teams in terms of whether the team or overarching system constitutes their primary focus of identification, affect inter-team information sharing and performance. In Study 1, we manipulate teams' foci of identification (team- or system-focused) in a sample of 84 five-member teams working in one of 21 four-team multiteam systems performing a computer strategy simulation. We find that, while system-focused teams shared information equally with all teams, team-focused teams shared less information with system-focused teams than they did with other team-focused teams. Inter-team information sharing positively predicted inter-team performance. In Study 2, we test the assumptions underlying our theory in a vignette experiment, demonstrating that team-focused individuals adopt instrumental motives toward inter-team interaction. Finally, in Study 3, we investigate the implications of system composition in terms of team identity foci by means of a simulation study based on the empirical results of Study 1. The results of the simulation yield novel propositions about the non-linear effects of social identity in multiteam systems.