This paper studies the long-term effects of technology and know-how transfers on structural transformations. In the 1950s, the Soviet Union supported the construction of the 156 Projects, which were large-scale, capital-intensive industrial clusters in China. These projects included a technology transfer, consisting of state-of-the-art Soviet machinery and equipment, and a know-how transfer, via the training of Chinese engineers, production supervisors, and high skilled technicians by Soviet experts. We use newly assembled data that follow steel plants for over four decades, and we exploit natural variation in the transfers they eventually received. We find that, while production advantages stemming from Soviet technology faded away if not complemented with training, the know-how transfer had a long-lasting impact on plant performance, stimulated technology upgrade when China was a closed economy, and increased exports to the Western world when China engaged in international trade. The know-how transfer also generated productivity and technology spillovers onto complementary establishments. Presented at: NBER Summer Institute on Productivity, Development and Entrepreneurship, AFA(scheduled), Harvard, UCLA, Yale University, University of British Columbia, University of Michigan, George Washington University, Auburn University, University of Oxford, LUISS, , Universitá di Bologna, Universitá di Padova, University of Melbourne, Tsinghua University, the Cliometrics Conference, the NBER Productivity Lunch, the Second Women in International Economics (WIE) Conference, the CEPR/LEAP Workshop in Development Economics, the Barcelona GSE Summer Forum on the Economics of Science and Innovation, the Pacific Conference for Development Economics, the Webinar Series in Finance and Development (WEFIDEV), the LSE Asia Economic History Seminar, the Online Economic History Workshop, and the Ridge Conference