In 1968, the humanitarian and development charity Oxfam asked a simple question: does aid work? What this meant in practice was that it appointed Bernard Llewellyn as its first Aid Appraiser. His conclusions were that roughly 50 percent of most aid work was wasted and ill-spent, too often on what he disparaged as ‘monuments to human folly’. That the organisation continued to support such initiatives he blamed on the ‘Oxfam bias’. There was always somebody to claim that aid worked. Llewellyn’s criticisms, and those who followed him, were acknowledged but the sector has been able to absorb them and move on. Indeed, a development studies literature has pointed to the self-perpetuating nature of aid work more generally: the ‘anti-politics machine’. One consequence has been that, if it is not known what works, then it is not known either what contribution charity has to the mixed economy of overseas welfare. That this has never been determined is not only a reflection of the ongoing disputes about the meaning of charity itself but also the reason for its subsequent growth.