This project continues a line of research focusing on the evolution of female participation in the labor force in the United State from 1790 to the present. The investigator has produced nine papers under the previous NSF award looking at various aspects of women in the work force. In particular, the increased participation of women in the work force over the past two centuries can be explained, in large measure, by the expanding menu of jobs, a decreased cost of acquiring skills, and a rise in the return to general knowledge. In addition, a number of data sets were constructed on female labor-force participation rates, earnings, occupations, job experience, education, and hours worked. The purpose of this project is to complete a monograph on the evolution of women in the labor force, and to continue research on four different topics on the subject of gender differences in the economy. The four topics are: (1) Develop a long-run data series on labor-force participation rates, occupations, and hours worked; (2) Analyze and explain the gender earnings-gap; (3) Analyze sex discrimination in earnings and occupations, including testing directly the Becker model of discrimination; (4) Analyze the effects of protective labor legislation on female employment. This research is important because it will provide a deeper understanding of the changing role of women in the market economy and the origin and causes of gender differences in terms of occupations and earnings.