Cognitive health is an important dimension of well-being in older ages, but few studies have investigated cognitive health in sub-Saharan Africa’s (SSA) growing population of mature adults (= persons age 45+). We use data from the Malawi Longitudinal Study of Families and Health (MLSFH) to document the age and gender patterns of cognitive health, the contextual and life-course correlates of poor cognitive health, and the understudied linkages between cognitive and physical/mental well-being. Surprisingly, the age-pattern of decline in cognitive health for both men and women is similar to that observed in the U.S. We also find that women have substantially worse cognitive health than men, and experience a steeper decline of cognitive ability with age. Strong social ties and exposure to socially complex environments are associated with higher cognitive health, as is higher socioeconomic status. Poor cognitive health is associated with adverse social and economic well-being outcomes such as less nutrition intake, lower income, and reduced work efforts even in this subsistence agriculture context. Lower levels of cognitive health are also strongly associated with increased levels of depression and anxiety, and are associated with worse physical health measured through both self-reports and physical performance.