A large percentage of poor children live with just one parent, usually their mother, and single-parent families are more vulnerable to economic downturns than are two-parent families. Living arrangements also affect the optimal design of policies related to income support and child support. In this paper we briefly review changes in family structure and the relationship between family structure and employment, and then focus on policies that are essential to reducing poverty in the context of the current work-based safety net, in which low-income families with children rely increasingly on mothers’ earnings. We argue that economically vulnerable families will benefit the most from policies that support resident parents’ efforts to balance work and caretaking, and that support and enforce nonresident parents’ contributions. We highlight key policies that help resident parents balance responsibilities, including support for access to child care and preschool, family-friendly workplace policies, and earnings supplements (e.g., the EITC). We also outline a set of policies designed to support and require nonresident parents’ contributions, including reforms aimed at creating a child support enforcement system clearly focused on improving child well-being, rather than government cost recovery, and policies supporting nonresident parents’ ability to work and pay support.