This open access handbook examines the phenomenon of South-South migration and its relationship to inequality in the Global South, where at least a third of all international migration takes place. Drawing on contributions from nearly 70 leading migration scholars, mainly from the Global South, the handbook challenges dominant conceptualisations of migration, offering new perspectives and insights that can inform theoretical and policy understandings and unlock migration’s development potential. The handbook is divided into four parts, each highlighting often overlooked mobility patterns within and between regions of the Global South, as well as the inequalities faced by those who move. Key cross-cutting themes include gender, race, poverty and income inequality, migration decision making, intermediaries, remittances, technology, climate change, food security and migration governance. The handbook is an indispensable resource on South-South migration and inequality for academics, researchers, postgraduates and development practitioners.