The paper calls attention to social capital as a situational and dynamic phenomenon. First, Coleman's definition is discussed to show the ambiguity and plurality of the various forms that social capital can take. In the second part, some applications of the concept are analysed as both an individual and collective resource. This allows to show why social capital is a contingent result of interactions among actors with different ends, which are shaped by the institutional context in terms of opportunities and constraints. Therefore, social capital can bring about different outcomes. This perspective is discussed selecting research findings in the field of comparative economic development, political modernization and government performance. Overlooking the situational and dynamic features of social capital is responsible for a reductive and stereotyped view of economic and political developments which is shared by some well-know studies based on social capital.