Using the National Education Longitudinal Study of 1988 (NELS:88) data sets, the complex phenomenon of intra-individual and inter-individual differences in and the potential predictors of those differences on career aspirations development over a 12-year period was analyzed. Results indicated that 73.1% of the total growth (change) in adolescents' occupational aspiration prestige scores were achieved between grades 8-10, while 26.9% of growth was achieved between grades 10 and 12. One-third of the total growth in the occupational aspiration scores of these individuals as young adults was observed between high school graduation and 2 years after graduation, while 67.4% of the total growth was obtained during the period between 2 and 8 years after high school graduation. Individuals with higher initial aspiration scores experienced slower growth in aspirations than those with lower initial aspirations. A negative association between career aspiration prestige scores in grade 12 and 8 years post-graduation existed. (Contains 1 figure and 5 tables.)