We analyze whether mothers’ parental leave decisions depend on their coworkers’ decisions. The identification of peer effects bears various challenges due to correlated characteristics within social groups. We therefore exploit quasi-random variation in the costs of parental leave induced by a policy reform in Germany. The reform encourages mothers to remain at home during the first year following childbirth. Administrative linked employer-employee data enable us to assign a peer group to individuals who work in the same establishment and occupation. Our results suggest that parental leave decisions are significantly influenced by coworkers’ decisions.