When their children are born, most unmarried parents have high expectations for the future, but they are particularly vulnerable to financial and relationship instability. Their children are disproportionately likely to experience negative health and wellbeing outcomes, in part because of low father involvement. We provide an overview of the findings in this area, drawing primarily from the Fragile Families and Child Wellbeing Study and two studies conducted by the Child and Family Research Partnership at The University of Texas at Austin. We conclude that father involvement is largely a function of parental relationship quality, and that interventions designed to improve child outcomes should focus on enhancement of co-parenting skills.