Abstract: This thesis comprises two complementary approaches that study the determinants of growth rates and per capita income levels in the long run and analyze the possibility of growth divergence among countries. The first approach focuses on the determinants of technological change, particularly, on the role played by policies and the country’s technological knowledge on the economies’ adoption and innovation capacities. The model is capable of explaining a wide set of equilibria; for instance, economies that are trapped in a low growth equilibrium,countries growing at a high rate in the long run and economies that despite sharing the same long run growth rate exhibit di¤erences in income levels. The paper discusses alternatives to escape growth traps which are related to improvements in the country’s adoption capacity and to the target of technology goals that are plausible according to the stock of knowledge and the productivity of the economy. Under certain conditions, trying to adopt frontier technologies may di¢ cult the process of growth. The second paper analyzes howthe exploitation of natural resources determines the incentives to accumulate physical and human capital and to develop labor or capital intensive sectors. In contrast with previous literature that stresses that the exploitation of natural resources is harmful for development, this study identifies new channels that show positive effects of this exploitation. There is only one speci c case, in which the exploitation of a particular type of natural resources is detrimental for development.