In this article, we review what has been learned to date from the first 5 years of the Fragile Families and Child Wellbeing study about child support, fatherhood, and marriage. The article first describes the parents' circumstances at the time of the child's birth, then examines the trajectories of parents' relationships (with each other and others), fathers' financial contributions and other indicators of fathers' involvement with their children 5 years later; and finally reviews what has been learned about the effect of child support enforcement on these three aspects of families' lives. We find that most unmarried parents are either cohabiting or romantically involved at the time of the child's birth, but are a distinctly disadvantaged group as compared with married parents. Five years later, most of these parents are no longer romantically involved, however, most of the fathers are still seeing their children on a regular basis, and about half are contributing either formally or informally to their support. Strong child support enforcement appears to increase formal and decrease informal support from fathers, reduce marriage among parents, and have a weak positive effect on father involvement. More research is necessary to understand whether these findings are robust over time and across samples of unmarried parents.