Publication Type: Conference Paper/Unpublished Manuscript Review Method: Peer Reviewed Abstract: Social capital reflects a way of conceptualizing how cultural, structural, and institutional aspects of small to large groups in a society interact and affect economic and political change. It is a core concept of a synthesizing framework that can be applied whenever collective endeavors of individuals are critical in achieving a collective goal. We identify trustworthiness, networks, and institutions as three basic forms of social capital. theories of collective action, especially its second-generation versions that incorporate heterogeneous preferences of individuals, are the key building blocks in constructing a theoretically sound social capital perspective.We think that one of the most important reasons why the concept of social capital appears to be so ambiguous is an often-unnoticed divide within the social capital camp itself. One set of social capital researchers bestows priority to a group's cultural factors (summarized in this paper as people's trustworthiness). Others maintain the mainstream neoclassical approach in which values and cultural factors are epiphenomenal to structural incentives.We take the non-reductionist view that trustworthiness - a term referring to the characteristics of individual preferences that facilitate individuals to behave cooperatively in social dilemmas even in the absence of structural and institutional incentives to do so - is not only a non-reducible but also a critical form of social capital.