Although cohort and country differences in average cognitive levels are well established, identifying the degree and determinants of inequalities in old age cognitive functioning could guide public health and policymaking efforts. We use all publicly available and representative old age surveys with comparable information to assess inequalities of cognitive functioning for six distinctive age groups in 29 countries. We document that cognitive inequalities in old age are largely determined by earlier educational inequalities as well as gender differential survival rates. For example, a one percentage point increase in the Gini index of past education is associated with an increase of 0.45 percentage points in the Gini index of delayed recall and 0.23 percentage points in the Gini of immediate recall. Results are robust to a variety of alternative explanations and persist even after controlling for gender-related biases in survival rates. Furthermore, we find evidence that unequal opportunities for education −captured by differences in parental background and gender- also have significant effects on inequality of old age cognition.