The authors investigated trends over a 13-year period in the predictive validity of assessment center data for objective career advancement for a sample of 456 academic graduates. Using year of entry and tenure as controls, findings from research into managerial effectiveness and development were confirmed with respect to the importance of interpersonal effectiveness, firmness, and ambition for long-term career success. Within the long-tenured group the validity of the overall assessment rating (OAR) corrected for initial differences in starting salaries and for restriction in range, was 0.35. Substantial long-term validities were obtained for ratings from the assessment center exercises. Computation of validities after three to five years of tenure of the same cohort in addition revealed some dynamic validity patterns. For instance, the OAR was important for early and late career success only for the group that was still present after 12 years, and its validity increased over time.