Cognitive abilities are fundamental for decision-making, and understanding the causes of human capital depreciation in old age is especially important in an aging society. Using a longitudinal labor survey that collects direct proxy measures of cognitive skills, we study the effect of educational attainment on cognitive performance in late adulthood in South Africa. We find robust evidence that an increase in a year of schooling improves memory performance and general cognition. We also find evidence of heterogeneous effects of educational attainment on cognitive performance. We explore the mechanisms through which education can affect cognitive performance. We show that a more supportive social environment, improved health habits, and reduced stress levels likely play a critical role in mediating the beneficial effects of educational attainment on cognition among the elderly.