This article uses a nationally representative data set to determine the role of glass ceiling barriers and cohort effects on the earnings differences between women and men in an elite and growing group of professionals: Scientists and engineers. It draws on national data gathered in four surveys during the 1990s for cohorts graduating between 1955and1990.Results indicate a continuing pay gap net of human capital, family status, and occupational characteristics that was not fully explained by either cohort effects or the glass (...) ceiling. The authors suggest that the gender pay gap in these fields results from several unmeasured barriers that neither worsen across the life cycle nor become less problematic for recent cohorts. Improvements will require continued attention to discriminatory barriers. (shrink)