This brief focuses on the role of fathers in contributing to children's well-being. The brief notes that collecting better data on fathers is vital to federal and state efforts to reform the welfare and child support systems and that understanding fathers' roles in their children's lives could help parents and social service providers better understand child development and meet children's needs in single-mother households. The brief reports findings contributing to the growing consensus among social scientists that fathers make unique contributions to their children's lives. Also cited is research suggesting that engaging fathers in the lives of their children, whether they can pay child support or not, has positive effects on the children and may motivate fathers to help support their children. Noting that information on fathers most likely to have a child on welfare is lacking, the brief describes three research efforts of the National Institute of Child Health and Human Development: (1) finding "missing men," testing ways to identify individuals such as fathers with no fixed address who are often missed in Census counts; (2) understanding fragile families by locating fathers at hospitals in the hours after their child's delivery and tracking the father-child relationship during the child's early years; and (3) learning from the Early Head Start program, examining the impact of efforts to involve low-income fathers in the lives of their young children at Early Head Start sites. The brief also describes the work of the Fatherhood Initiative seeking to foster greater father involvement and to improve the collection of data on fathers. (KB)