This chapter aims to study the forms of technical assistance in Toyoda de México and its successor, Siderúrgica Nacional (Sidena), in the context of Mexico’s Import Substitution Industrialization (ISI) policies. The former was mainly dedicated to the specialized production of capital goods for the textile industry and the latter to the production of steel for the railroad and automotive industries, as well as for the manufacture of tractors, in a period that includes the years immediately after World War II. The objective is to study the differences, continuities, and processes of change generated dynamically according to the changing historical conditions of the capital goods industry. It is interesting to reflect on the assistance programs from the perspective of technological adaptation and resignification and the technical and administrative cadres mobilized based on technical assistance agreements. The Toyoda and Sidena cases are laboratories in which technical assistance, the uses of technologies and their portability, and adaptation processes are expressed.