Objective: Positive associations between education and late-life cognition have been widely reported. This study examines whether occupational complexity mediates the relationship between education and late-life cognition, and whether the magnitude of mediation differs by race, gender, or education level. Methods: Data were from a population-based cohort of non-Hispanic Blacks and Whites aged ≥45 years (n = 7,357). Education was categorized as less than high school, high school, some college, and college or higher. Using linear regression, we estimated the direct effect of each successive increase in education on cognitive functioning and indirect effects via substantive complexity of work. Results: Occupational complexity significantly mediated 11%-22% of the cognitive gain associated with higher levels of education. The pattern of mediation varied between White men and all other race-gender groups: among White men, the higher the education, the greater the mediation effect by occupational complexity. Among Black men and women of both races, the higher the education, the smaller the mediation effect. Discussion: Higher levels of education may provide opportunity for intellectually engaging environments throughout adulthood in the form of complex work, which may protect late-life cognition. However, this protective effect of occupational complexity may not occur equally across race-gender subgroups.