Although research increasingly focuses on nonresident biological fathers, little attention has been given to the role of other men in children's lives. The authors examine the factors associated with social father presence and their influence on preschoolers' development. Findings indicate that the majority of children have a social father and that mother, child, and nonresident biological father characteristics are all related to social father presence. These associations differ depending on whether the social father is the mother's romantic partner or a male relative. The social father's influence on children's development also depends on his relationship to the child. Male relative social fathers are associated with higher levels of children's school readiness, whereas mothers' romantic partner social fathers are associated with lower levels of emotional maturity.