This paper tests the central tenet of social psychology and the life-course perspective that broader contexts of opportunity and constraint moderate the ability of individuals to act on their plans and ambitions. We use the 1972 National Longitudinal Study to assess the impact of mastery on achieving one's occupational expectations and to determine if the benefits of mastery are contingent on structural contexts. Three types of structural constraints are examined: local employment conditions, marriage and family, and the credentialing of upper-status occupations. In general, mastery is associated with more ambitious and stable expectations over time. Results from discrete-time event history models show that personal mastery is positively associated with achieving one's occupational expectations, and the association is contingent on some, but not all, structural constraints. Marriage increases the effect of mastery on the odds of achieving one's occupational expectations, but having children decreases mastery's effect. Mastery is more beneficial to those pursuing training-intensive occupations, partly due to the acquisition of post-secondary credentials. Lastly, women receive less of a benefit from mastery than men do, likely due to the structural barriers women face in the workplace. Contrary to expectations, poor local employment conditions do not weaken mastery's influence on goal attainment. (Contains 5 footnotes and 4 tables.)