We develop a theory of marriage and fertility, distinguishing the choice to have children from the choice of the number of children. The deep param eters of the model are identified from the 1990 US Census. We measure voluntary and involuntary childless-ness, and explain why (1) single women are more often childless than married women but, when mothers, their fertility are almost similar; (2) childlessness exhibits a U-shaped relationship with education for both single and married; (3) the relationship between marriage rates and education is hump-shaped. We show how family patterns have been shaped by the rise in education and wage inequality, and by the shrinking gender wage gap.