Cohort purpose: The Mature Adults Cohort of the Malawi Longitudinal Study of Families and Health (MLSFH-MAC) contributes to global aging studies by providing a rare opportunity to study the processes of individual and population aging, the public health and social challenges associated with aging and the coincident shifts in disease burdens, in a low-income, high HIV prevalence, sub-Saharan African (SSA) context. Design and Measures: The MLSFH-MAC is a population-based cohort study of mature adults aged 45 years and older living in rural communities in three districts in Malawi (Mchinji, Balaka and Rumphi). Initial enrollment at baseline is 1,266 individuals in 2012. MLSFH-MAC follow-ups were in 2013, 2017, and 2018. Survey instruments cover aging-related topics such as cognitive and mental health, NCDs and related health literacy, subjective survival expectations, measured biomarkers including HIV, grip strength, hypertension, fasting glucose, BMI, a broad range of individual- and household-level social and economic information, a 2018 qualitative survey of mature adults and community officials, 2019 surveys of village heads, health care facilities and health care providers in the MLSFH-MAC study areas. Unique features: MLSFH-MAC is a data resource that covers 20 years of the life course of cohort members and provides a wealth of information unprecedented for aging studies in a low-income SSA context that broadly represents the socioeconomic environment of millions of individuals in south-eastern Africa. Among these are the longitudinal population-based data on depression and anxiety using clinically-validated instruments. MLSFH-MAC is also vanguard in measuring longitudinal changes in cognitive health among older individuals in SSA. Complemented by contextual and qualitative information, the extensive MLSFH-MAC data facilitate a life-course perspective on aging that reflects the dynamic and distinct settings in which people reach older ages in SSA LICs. Across many domains, MLSFH-MAC also allows for comparative research with global aging studies through harmonized measures and instruments. Collaboration and data access: Public-use version of the 2012 (baseline) MLSFH-MAC data can be requested at http://www.malawi.pop.upenn.edu. Sharing of additional MLSFH-MAC data is currently possible as part of collaborative research projects (if not overlapping with ongoing research projects, and subject to a Data Use Agreement).