In “Fatherhood, Cohabitation, and Marriage,” Wade F. Horn, Assistant Secretary for Children and Families at the Department of Health and Human Services, summarizes the importance of fathers to child well-being. He explains that “fatherlessness is a significant risk factor for poor developmental outcomes for children.” This connection has led some observers to view cohabitation as a substitute or at least an alternative to marriage. Horn argues, however, that marriage is the best option for children and that cohabitation is a weak family structure compared with marriage. Children in households with married parents do better on almost every measure of child well-being, even after controlling for income.