Migration between the countries of the Global South, otherwise known as South-South migration (SSM), accounts for nearly half of all international migration, reaching almost 70% in some places. The potential of SSM to contribute to development and delivery of the SDGs is widely acknowledged but remains unrealised, largely due to existing inequalities at the global, national and local levels which determine who is (and is not) able to migrate, where to, and under which terms and conditions. These multidimensional inequalities are associated with a lack of rights for migrants and their families; difficult, expensive and sometimes dangerous journeys; and limited opportunities to access services and protection, which can, in turn, exacerbate inequalities. The challenge of ensuring that SSM reduces inequalities and contributes to delivery of the SDGs is intractable due to: - A lack of evidence about the ways in which horizontal and vertical inequalities can undermine major development investments and policies, and about the types of interventions which can overcome inequalities associated with SSM; - A failure of existing development approaches to take account of how SSM (and related policies) is/are influenced by broader economic, political and social processes (and relevant sectoral policies); - A focus on individual ODA-recipient countries rather than on dynamic effects along migration 'corridors' which connect origin and destination countries and the development implications of (two-way) flows of people, finance, trade and knowledge; - The politicisation of migration and a growing tendency to focus on migration management and border controls at the expense of equitable migration and development related outcomes; - The top-down, high-level orientation of much development policy planning which can dehumanise migrants by focusing on economic indicators and outcomes rather than experiences and well-being, broadly defined; and - A gap between policy and legal frameworks to limit inequalities associated with SSM (where these exist), and their equitable delivery / implementation in practice. The Hub is oriented towards addressing this challenge and ensuring that SSM is able to make a more equitable and effective contribution to poverty reduction, development and delivery of the SDGs, particularly SDGs 1, 5, 8 and 10. It does so by bringing together, for the first time, research and delivery partners from 12 ODA-recipient countries which constitute six SSM 'corridors' (Burkina Faso-Cote d'Ivoire, China-Ghana, Egypt-Jordan, Ethiopia-South Africa, Haiti-Brazil, Nepal-Malaysia) who will work in partnership with five UN agencies and the OECD. The Hub will deliver challenge-led programmes of research and evaluation to address inequalities associated with SSM, undertaking extensive new data collection and policy analysis, and testing interventions and solutions in a range of geographical contexts. The Overseas Development Institute (ODI) will lead the Hub's communication and dissemination work, working alongside our research partners in the Global South to develop a range of outputs for different local, national and global audiences to maximise the Hub's impact on policy and practice. The Hub builds on existing RCUK investments but also develops equitable new partnerships in order to generate novel and innovative perspectives on the intractable challenge which it seeks to address. In particular, by bringing together researchers from the Global South working across the countries making up the SSM corridors, and connecting these teams with leading migration scholars in the Global North, the Hub provides an opportunity for significant cross-learning within and between the corridors, and on SSM more generally. In so doing it offers considerable added value, strengthening capacity and capability for understanding - and responding to - the challenges associated with SSM and delivery of the SDGs.