Objective: We investigated complexity of work in main occupation in relation to incident cognitive impairment in older Puerto Ricans. Method: A population-based sample of 1,673 adults age 60+ for the Puerto Rican Elderly: Health Conditions (PREHCO) study was used. Cognition was measured at baseline and 4 years later using the Mini-Mental Cabán (MMC), with scoring 1.5 SD below the MMC score adjusted for age, education, gender, and reading ability comprising cognitive impairment. Complexity scores were derived from the 1970 U.S. Census, 1977 and 2000 Dictionary of Occupational Titles, and 2001 O*Net. Results: Controlling for baseline age, gender, childhood economic hardship, adult money problems, depressive symptoms, and self-reported health, greater scores for most work complexity measures were associated with significantly lower risk of cognitive impairment (ps < .05), with significant odds ratios ranging between 0.74, reflecting 26% reduction in risk for every extra standard deviation of complexity, and 0.81. Controlling for education reduced these effects slightly but also reduced most associations to nonsignificant. The results were stronger for those with less childhood economic hardship or education (ps < .05). Discussion: Complexity of work may reduce risk of cognitive impairment in Puerto Rican older adults, especially when combined with favorable childhood economic conditions and higher educational attainment.