This commentary argues that the recently approved contract under which the Millennium Challenge Corporation (MCC) is investing US$437 million dollars in Niger over the next five years, most of it on large-scale irrigation, is not a good investment. The paper explains why the programme is not likely to achieve the benefits anticipated. MCC had commissioned a detailed feasibility study, carried out by the authors of this paper, which strongly argued against investing in large-scale irrigation, in part because there is a poor track record for these investments in Niger, and in part because MCC has no comparative advantage in such investments. Instead, the feasibility study presented a strong case for investing in small-scale rainwater harvesting for agriculture and livestock at farm and watershed levels; and individualised small-scale irrigation for high-value nutritious crops and other water uses. The commentary concludes with suggestions on how the funds allocated for large-scale irrigation infrastructure (about US$250 million) could be reallocated to benefit a far larger number of people; and a recommendation that investors in African agricultural water management projects carry out an assessment of the performance and impacts of investment experiences over the past decade to identify lessons that could inform the next decade of investments in agricultural water management.