Men who have children with several partners are often assumed to be “deadbeats” who eschew their responsibilities to their children. Using data from the nationally representative National Longitudinal Survey of Youth 1997 cohort (NLSY-97), we show that most men in complex families intensively parent the children of one mother while being less involved, or not involved at all, with children by others. Repeated qualitative interviews with 110 low-income noncustodial fathers reveal that men in complex families often engage with and provide, at least to some degree, for all of the biological and stepchildren who live in one mother’s household. These activities often exceed those extended to biological children living elsewhere. Interviews also show that by devoting most or all of their resources to the children of just one mother, men in complex families feel successful as fathers even if they are not intensively involved with their other biological children.