Twin studies of Africans have been scarce although Africans have shown the highest twin birth rate in the world. As a parallel study of the South Korean Twin Registry, the Nigerian Twin and Sibling Registry (NTSR) was developed to understand causal influences on the development of cognitive abilities, personality, and mental health among Nigerians. Currently, 1,134 twins and 404 full- and half-siblings have been registered with NTSR. This article describes research background, goals, major recruitment strategies, measures, and future directions of the NTSR.