Across East Africa’s vast rangelands, pastoralist livestock systems have been commercialising since the early 1900s. Commercialisation has varied widely within and between areas, but now includes substantial livestock exports, regional and cross-border trade, and supply to domestic markets. This policy brief examines some of the key features of pastoralism that affect how commercialisation evolves in pastoralist societies, and why poorer producers often benefit least from new market access. The policy brief draws on a substantial body of research and programme evaluations, and two new APRA research reports on pastoral livestock commercialisation in south-east Ethiopia (Gebresenbet, 2020) and northern Kenya (Roba, 2020).