• childbearing;
  • childrearing;
  • cohabitation;
  • couples;
  • nonmarital childbearing;
  • nonmarital families

Cohabitation and childbearing outside of marriage are increasingly common family arrangements in the United States. Cohabitation is becoming more like formal marriage in that both are childrearing institutions. Attempts to study the meaning of families formed outside of marriage face the challenge of studying a moving target because the rapid rise in nonmarital families contributes to new meanings and institutional supports. Among these institutions are state policies that formalize ties between members of nonmarital families. This review summarizes the changing demography of cohabitation and nonmarital childbearing, considers the causes and effects of these changes, and describes some recent policies that formalize the relationship between members of families formed outside of marriage. These policies may affect family members' behavior.