The changes in career development and upward mobility in response to recent changes in the U.S. labor market were examined in a study that included an analysis of data from the National Longitudinal Survey of Young Men and the National Longitudinal Survey of Youth. Analysis of the data, which covered the period 1966-1994, established that the transition into the labor market has changed noticeably. Young people are taking longer to complete their schooling, are significantly more likely to work while in school, and are more likely to hold service sector rather than goods-producing jobs once out of school. Wage attainment has deteriorated, and job instability has increased. Economic mobility has declined and become more unequal, and the prevalence of low-wage careers has increased from 12% in the original cohort to 28% in the recent cohort. The following policy strategies were recommended as ways of restoring the "American dream": constructing external career ladders; constructing or strengthening internal career ladders; improving low-wage jobs; and improving labor market coordination. Information about the following items is appended: variable definitions and construction; validation and attrition analysis for the job change measure; relative distribution measures; and permanent wage estimation. (Contains 78 tables and 221 references.)(MN)