Employing 1970 U.S. census data, tests were conducted to examine the empirical evidence on the existence of U.S. labor market segments. Some comparisons between the labor market for males and females were made, but the analysis concentrates on males. Labor markets were divided by race, sex, job types (secondary, primary subordinate, primary independent, and crafts) and industry types (public and private). The basic concern was with intra-segment economic position, defined as annual earnings. One hypothesis tested was that mobility between occupational and industrial segments is limited for blacks and whites and males and females. Data analysis revealed that white males have much higher upward mobility out of secondary labor markets than do blacks. Regression estimates demonstrated that schooling and age are significant correlates of upward mobility for males. In comparing male and female regression estimates by segment it was found that women receive lower salaries than men and generally get a lower pay-off to additional schooling and higher age. Overall study results, while neither proving nor disproving the existence of a segmented labor market, indicate considerable stability over a five-year period in types of jobs and industries people work in, large earnings differences among occupational segments and private industries, and the relationship among education, work experience, and earnings differing among job types but not between industry types. (CSS)