This study examines the determinants of women's return to work following the birth of their first child among white, black and Mexican-origin women to test the general hypothesis that previous racial differentials--observed during the later 1960s and early 1970s--in employment of new mothers have disappeared with changes in overall employment patterns of women. Data from the National Longitudinal Survey of Youth show the expected pattern. Several important measures of a woman's human capital, such as value of time, job experience, and work role attitudes have similar effects in predicting postnatal force participation for the three groups. However, other human capital and demographic factors, especially education, family income other than the woman's earning, and residence in an urban area affect return to work differently for black and white mothers. The results are tied to changes in job characteristics, the economy, and the family.