This article analyzes the relationship between social capital and economic growth for a panel of developed and developing countries during the period 1990-2004, using static and dynamic panel data method and a simultaneous equations model. The main results of this study are, first, the level of social capital and growth are significantly and positively correlated, on the other hand, a high level of social capital as an indirect effect on economic activity through its effect on institutional development. The results support the fact that the improvement of the social infrastructure with high levels of trust and cooperation between individuals not only a direct but also an indirect effect on economic growth through the development of institutions in economy.