This paper investigates coworker peer effects in parental leave usage in Sweden. Weuse an instrumental variable approach labeled peers of peers in which parental leave usage byfamily peers (siblings and cousins) of coworkers is used as an instrument for coworkers’parental leave usage. For fathers, we find that a 10-day increase in average parental leave usageamong coworkers increases usage by approximately one and a half days, while for mothers,the increase is approximately one day. The results are robust to alternative model specifications.We explore possible mechanisms and discuss policy implications.