Following changes to federal cash assistance programs in 1996, low-income families now rely on a set of social programs: the Earned Income Tax Credit, food assistance, publicly funded health insurance, and child-care subsidies. In this review, we present evidence on the effects of these programs on families' economic circumstances, families' psychological well-being and functioning, and children's developmental outcomes. Social safety net programs improve families' economic circumstances, thereby achieving their primary goal. Few studies have examined impacts on children's developmental outcomes but overall, programs improve children's academic, behavioral, and physical well-being. Even fewer studies have examined impacts on parents' psychological well-being or family functioning, leaving gaps in the literature. The review concludes with discussions of the Great Recession and whether effects found during stronger economic times generalize to the most recent economic crisis, and with a discussion of social safety net policies in countries outside the United States. © 2013 The Society for Research in Child Development.