This special labor force report, focusing on children of working mothers, summarizes findings from the 1977 annual survey of marital and family characteristics of workers in the population who are 16 years old and over. Data are given on: the numbers of children of various ages with working mothers, the percentages of black and white children living with a single parent, the number of children either wholly or partially dependent on their mother's earnings for a large share of their support; and the average size of families of working and nonworking mothers. The following supplementary tables, each dated March 1977, are provided in the appendix: (1) Number of own children under 18 and family income in 1976, by age of children, type of family and employment status of parents; (2) Number of own children under 18 and median family income in 1976, by age of children, type of family, employment status of parents, race and Hispanic origin; (3) Number of families with own children under 18 and family income in 1976, by age of children, type of family and employment status of parents; and (4) Number of families with own children under 18 and median family income in 1976, by age of children, type of family, employment status of mother, race and Hispanic origin. (Author/SS)