High rates of nonmarital childbearing combined with considerable union instability portend that a large proportion of children can expect to spend time with a ‘social father’ (i.e., a man who is married to or cohabiting with their mother but to whom they are not biologically related). Prior evidence, primarily about stepfathers, suggests that children growing up in social-father families have similar developmental outcomes to children in single-mother families, and that both groups exhibit considerably worse developmental outcomes than children in two-biological-parent families. These differences are likely due in part to differences in resources and parenting practices across family types; social-father families also tend to be less stable (face a greater likelihood of parental union dissolution) than two-biological-parent families.

 In contrast to early research, more recent evidence from the Fragile Families and Child Wellbeing Study, which focused on unmarried parents and their children, reveals relatively high-quality parental investments among social-father families that are formed after couples break up and mothers repartner. Specifically, after a nonmarital birth, mothers tend to repartner with men who have higher levels of economic capabilities than their children’s biological fathers, these men tend to be highly involved with the mothers’ children, and such involvement is positively associated (cross-sectionally, at least) with children’s well-being; maternal repartnering is also associated with declines in maternal depression and material hardship. Thus, at least in the short term, families where mothers repartner after union dissolution tend to be relatively advantaged compared to those who do not repartner. Yet, it is unclear whether relatively high socioeconomic capacities and high-quality parenting behaviors persist over time among social-father families that stay together, and whether better social-father characteristics and parenting behaviors are themselves associated with subsequent family stability.

 We use data from the Fragile Families and Child Wellbeing Study over years 1 through 9 after a child’s birth with a series of ordinary least squares, random-effects and fixed-effects regression models to examine whether high-quality social father characteristics and parenting behaviors: (1) tend to persist or fade over time, overall and as compared to intact biological-father families, and (2) are predictive of family stability over time. These analyses will shed new light on the relative risks and benefits of maternal repartnering for children, including the quality of parenting to which children in social-father families are exposed over time, and the extent to which maternal repartnering with a high-quality social father is likely to result in a stable family environment. Results have implications for marriage promotion and family formation policies and programs, as well as for interventions to promote wellbeing for children in complex families. Given that a sizeable proportion of children will likely spend time with a social father during childhood, this study may have important implications for children’s well-being.