Multi-partner fertility leads to complex relationships that fathers must navigate. They have ongoing relationships with current and past romantic partners who are the mothers of their children; they also have children who may or may not live with them and to whom they may or may not be biologically related. In this paper, we draw on quantitative data from the National Longitudinal Survey of Youth—1997 Cohort and qualitative data from in-depth interviews of over 100 low-income fathers to examine how fathers experience and respond to multi-partner fertility.

First, we provide a longitudinal examination of the level and distribution of fathers’ involvement with their children. We find that while involvement with nonresident children declines over time, fathers often maintain high levels of involvement with at least one biological or social child. From a father’s perspective, this results in continuous investment in children, just not in the same children. Few fathers with multi-partner fertility, and almost no low-income fathers with multi-partner fertility, allocate their time and financial resources evenly across all their children. At the other extreme, few fathers “swap kids” by eliminating contact with older non-residential children completely once new children are born to new partners.  Instead, the majority of fathers with multi-partner fertility experience a process of “crowding out,” whereby resources of time and money devoted to older, non-residential children gradually decline while resources devoted to new biological and social children gradually increase.  

We then use qualitative data to discuss fathers’ motivations for having children with multiple partners, despite the financial and relationship challenges that result. We find that having a child with a new partner (and fathering her other children) gives economically marginal men another chance to succeed in their role performance as fathers, even if they may have failed with their older children. They do not have to father all their children well at the same time, just one of them, and the focus on the new child allows them to ignore previous failures. We conclude by discussing how fathers’ responses to family complexity might inform the design and administration of safety net policies.