Coleman’s Foundations devotes much attention to the role of ‘social capital’ in solving problems of cooperation in dilemma situations. In contrast to the human capital approach, however, there is no stringent theory of social capital allowing for the deduction of empirically testable hypotheses from a set of general principles. This article demonstrates by means of various examples that social capital is an important exogenous factor inducing the evolution of cooperation and the stabilization of cooperation in N-person dilemmas. Some preliminary suggestions (...) are made concerning the measurement of social capital and its ‘rate of return’ as a productive factor contributing to the cooperative solution in dilemma situations. (shrink)