Policy makers, journalists and other commentators have hailed genetically modified (GM) crops as a ‘pro-poor’ success in the developing world. Their confidence appears to be justified by the encouraging conclusions reached by academic studies on the performance and impacts of GM crops, which seem to provide convincing evidence of substantial benefits for smallholders in developing countries. However, a detailed, critical examination of studies on transgenic, insect-resistant cotton in China, India and South Africa demonstrates that the technology's impacts have been evaluated and represented in selective and misleading ways. The performance and impacts of GM crops have in fact been highly variable, socio-economically differentiated and contingent on a range of agronomic, socio-economic and institutional factors. The shortcomings of the GM crop-impacts literature have done a disservice to public and policy debates about GM crops in international development and impeded the development of sound, evidence-based policy.