The book introduced herein is a true classic of contemporary Political Science and, as such, it is a fully right decision to include it in the new collection of "Contemporary Classics" edited by the Sociological Research Center. Since the book appearance, and in less than 20 years, Putnam managed to catapult the concept of "social capital" from a strictly academic environment to the world of international institutions and the scene of relations between government, market, and civil society. A concept that, although put into circulation before by other authors, since Putnam's contribution has reached usage levels that, although may be disputable from a strictly academic rationale, demonstrate the attractiveness of a formulation that, at least apparently, is able to explain situations, imbalances, and problems that are not easily accommodated in other formulations. The key point of the book lies on the willingness to explain the good performance of government institutions, although later on the concept's expansion capacity has proven to be far superior to that first effort.