Traces family demography development in United States, summarizing findings from research since 1940. Focuses on family life cycle, historical trends, intermarriages, socioeconomic status and family stability, the marriage squeeze, international trends in marriage, health issues, cohabitation, one-parent families, gender issues, divorce, and projections of marital status, remarriage, marital homogamy, stepfamilies, and recent changes in American family demographics. (Author/NB)