There is a growing social class divide in the American family. While the most-educated couples are enjoying greater stability in family life than in previous decades, the opposite is true for those at the bottom of the distribution. For men, in particular, the least educated are more likely to become fathers in their early twenties, to have children outside of a marital bond with more than one partner, and to live apart from them. Interviews with low-income black and white fathers in Philadelphia and Camden, NJ reveal several important factors about this process. First, there is little partner search or selectivity regarding the woman who will become his child’s mother. Second, pregnancies happen quickly in the relationship and are by and large not intended, though not avoided either. Third, news of a pregnancy is usually greeted with enthusiasm and sparks a “fatherhood thirst” which leads to the attempt to solidify the couple’s relationship “for the sake of the baby.” Yet because of the fragility of the couple’s bond, the relationships rarely survive until the child turns five, and men find it increasingly hard to stay in contact with the child once the relationship ends. The fatherhood thirst remains unsatisfied, which may drive further childbearing with a new partner. Understanding this dynamic suggests several points of intervention for policymakers. First, we should do more to reduce early and unplanned childbearing among young men, targeting key features of the relationship formation process that lead to such outcomes. Second, in keeping with efforts of on-the-ground programs associated with the “responsible fatherhood movement,” policymakers should do more to keep unmarried fathers connected with children, including assuring that those who pay child support have a visitation agreement that is enforced. Policy should clearly signal that fathers’ potential contribution as parents, not just as paychecks, is valued.