Based on information from supplementary questions in the March 1976 Current Population Survey, the report presents data which indicate that women are contributing increasingly to family incomes. Analysis of the information reveals that the marital composition of the American labor force has changed significantly since 1970. A rapidly growing youth population, high divorce rates, and a decline in labor force participation rates for married men account for the changes. In 1976, 14.9 million mothers with children under 18 were in the labor force. This participation was strongly influenced by education level, husband's income, and presence of children. Divorced mothers were more likely to work than other mothers, and never-married mothers were most likely to be unemployed. Many working wives with children did not work year round, full time. Black married mothers were more likely to work outside the home than whites, and the black wives contributed a greater proportion to family income than whites did. The labor force participation rate of married Hispanic women was nearly equal to that of white wives, but Hispanic husbands' participation rates were higher than blacks or whites. The bulk of the report contains tables of statistics. (Author/AV)