While extensive research has investigated the risks of children sharing their personal information online, little work has investigated the implications of parents sharing personal information about their children online. Drawing on 102 interviews with parents, we investigate how parents decide what to disclose about their children on social network sites (SNSs). We find that mothers take on the responsibility of sharing content about their children more than fathers do. Fathers are more restrictive about sharing to broad and professional audiences and are concerned about sharing content that could be perceived as sexually suggestive. Both mothers and fathers work to leverage affordances of SNSs to limit oversharing. Building on prior work, we introduce the concept of parental disclosure management, which describes how parents decide what to share about their children online. We also describe an emerging third shift of work that highlights the additional work parents take on to manage children's identities online. We conclude with theoretical and practical implications for designing SNSs to better support family life online.