In recent decades we've seen the emergence of a new generation of giant non-profit foundations funnelling billions into global development efforts, from education and culture to technology and public health.
The Bill and Melinda Gates Foundation is one of the largest, with an endowment of almost $40bn (£24bn). But it's not alone: the Ford Foundation, Hewlett Foundation and others are also big funders.
In the global south, however, suspicion lingers about the size and motives of these US-based organisations.
Hugh Muir examines the issues, asking where big philanthropy is heading, what challenges it faces, and how it could be done better. He is joined in the studio by Loren Treisman from the Indigo Trust, one of the charitable trusts held by the Sainsbury family, founders of one of the UK's largest supermarket chains.
Down the line from California is Jane Wales, CEO of the Global Philanthropy Forum, a network of philanthropists working in the developing world, while Preeti Sinha joins the debate from the African Development Bank in Tunis.
