Rural poverty in Africa is tightly linked with low agricultural productivity. Farmers in most of Africa make little use of irrigation, chemical inputs or commercial seed. Efforts to overcome structural and behavioural barriers to agricultural intensification have had at best modest success. Using evidence from more than a decade of studying farmers and farming in Ghana, Professor Udry shows how it is the lack of breakthrough technology, not farmers’ inability to adopt new technology, that lies at the root of stagnant agricultural productivity, and discusses possible routes out of the low-productivity trap.