The study presents the notional changes of the term 'social capital' in history, eventually providing a synthesized definition. It explains the character of the notion connected to the individual and the collective, its mechanisms of operation, effects, and the different perspectives on its measuring. The authors trace back the genesis of social capital to the recurrent cooperative situations that can be modeled by the notion of public goods and the prisoner's dilemma game. Finally, examining growth possibilities of social capital, the authors argue for a moderate state intervention.