Core A: Leadership and Administration Core—Abstract The Leadership and Administration Core (LAC) will provide scientific direction and organizational oversight to the entire Health, Aging and Dementia in South Africa: A Longitudinal Study (HAALSI) Program. LAC leaders and associates will be responsible for the scientific integrity of every stage of each project and the supporting work of the cores. The LAC is comprised of a hierarchy of three PIs, an Executive Committee, an External Advisory Committee with balanced South African and international representation, and core administration. The LAC will support each of the four projects and two other cores by establishing regular, responsive communication systems, and providing effective problem-solving, technical, and methodological support; supervision and administrative management; and research dissemination pathways. The LAC will also be responsible for the fiscal health of each project and core and the HAALSI Program overall. Finally, the LAC will provide effective engagement with Health and Retirement Study (HRS) sister studies; the South African Population Research Infrastructure Network (SAPRIN); the MADIVA project (Multimorbidity in Africa: Digital Innovation, Visualisation and Application) funded through DS-I Africa (Harnessing Data Science for Health Discovery and Innovation in Africa); African Wits-INDEPTH Partnership for the Genomic Study of Body Composition and Cardiometabolic Disease Risk (AWI-Gen)/Human Heredity & Health in Africa (H3Africa), and other affiliated scientists, in an effort to harmonize approaches with other global aging studies and population health research initiatives in South Africa.