The number of unemployed persons at some time during calendar year 1974 totaled 18.3 million which is nearly four million above the 1973 level. The number of persons who worked reached 101.7 million. The proportion of the population who work varies widely by age, and the pattern for men differs from that for women. Over this period, the rate for black women with work experience decreased while that for white women increased. Among men, a higher proportion of whites than of blacks worked during 1974. The total number of unemployed during 1974 was about three and one-half times the annual average. The increase in unemployment in 1974 was sharper for men than for women, but the proportion of the work force with unemployment during the year continued to be higher for women. Although the proportion of the work force with unemployment rose over the year in every age group, the rise was greater for persons under 25 and lowest among persons over 45. Descriptions of basic labor force concepts, sample design, estimating methods, and reliability of the estimates are given in a section called Explanatory Notes. Twenty-five supplementary tables are presented. (Author/EC)