Abstract : The aim of this Ph.D. thesis is to show that technological change is a determinant of long run growth and the dynamics of inter-country inequalities. Specifically, we try to show that technological change represents a channel through which the effects of education, capital market imperfections and institutions affect economic growth and long run convergence. We show that the distribution of human capital determines occupational choices of agents whose source of heterogeneity is the level of human capital, economic growth and convergence of a technologically backward economy. The rate of growth of a developed country depends positively on the amount of agents investing in R&D activities. The positive effect of human capital on economic growth is transmitted through technological change. We show that capital market imperfections imply a credit rationing of high-skilled agents and hence reduce economic growth. The effects of credits on economic growth is positive and realized through the technological change channel. We show that, in a democratic economy with high income inequalities, political corruption reduces the rate of taxation and the mean level of human capital, but increases the level of accumulation and the rate of economic growth when the contribution of human capital in the product is small.