Does over-education assist or hinder occupational advancement? Career mobility theory hypothesizes that over-education leads to a higher level of occupational advancement and wage growth over time, with mixed international empirical evidence. This paper re-tests career mobility theory directly using a rich Australian longitudinal data set. A dynamic random effects probit model is employed to examine upward occupational mobility, considering two-digit occupational rank advancement and wage growth over three-year intervals. The 'Household, Income and Labour Dynamics in Australia' data across nine years are employed, and a Mundlak correction model is adopted to adjust for unobserved heterogeneity effects and potential endogeneity, both of which are important to overeducation analysis. Contrary to career theory, the results point to job mismatch as an economic concern rather than a passing phase, regardless of whether or not workers are skill-matched. Results further show the importance of adjusting for endogeneity.