Quite a lot of economic activities feature “increasing returns to scale”. Very concretely and with the purpose of giving a clear example, the average cost of producing a single car is lower for those firms/economies already producing a lot of cars compared to those producing only few of them. Clearly, this gives a big advantage to those countries which are already developed and make the development process more complicated for those who are lagging behind. There is more than that: in most cases, modern production techniques (featuring increasing returns to scale) are only viable in those economic environments where people have enough money in their pockets to buy large quantities of commodities. Again, this is a mechanism making richer the rich and poorer the poor. In this chapter, using the seminal contribution of Paul Rosenstein-Rodan (The Economic Journal, 53, 202–211, 1943) and its theory of the “big push”, we try to understand what a “developmental state” should be and do. Two leading examples are Italy and Japan, where at a point of their history the governments played a leading role in the process of industrial development. The State was in charge of putting in place those businesses that private actors did not find profitable. The State built the conditions of profitability for future, private investments in the industrial sector. This chapter goes into the analytical details of this State-led model of economic development and discusses its risks and political feasibility.