This volume explores the diverse meanings and ways of implementing development programs and technical assistance projects, through several case studies grounded in Mexico but transcending its geography. Despite or perhaps because of claims of revolutionary nationalism , Mexico played a crucial international role during the decades following World War II, both by challenging and enacting developmentalist models, values, and projects that stressed national priorities, resonating beyond its borders and even outside Latin America. Energy, irrigation, communication infrastructures, nuclear technologies, public health, and patents, are meaningful examples explored in this volume of the mobilisation of science and technologies understood in a broad sense, including not only the natural and social sciences, but also bureaucratic technologies that accompanied infrastructural and industrial projects. These case studies interrogate the specific agents and mechanisms of technical assistance put to work to meet local priorities, which in turn required and informed different international models and ideas of development.