Created in 1948 in the core of the United Nations, ECLAC emerged as part of the construction effort to build new international institutions with the purpose to support regional development. Contraposing itself to the resurging of the classical theories over international trade - specially the ricardian principle about comparative advantages- ECLAC will present the thesis over the deterioration of the terms of exchange, denouncing the asymmetries of the international division of labor, which tended to perpetuate underdevelopment in the periphery and not to permit its industrialization. On the contrary of the originality of the theories and proposals of the 1950 s, ECLAC s thought would not be able to answer to the liberal offensive which was being happening since the 1970 s, following the deep changes in the international economic system. ECLAC s agenda in the 1990 s would be elaborated in a new context, after almost two decades of neoliberal experiment in the region. This work seeks to understand the reasons of ECLAC s incapacity to oppose itself to the thesis of the new liberal reformism, through an analysis about its trajectory in the last fifty years.