During the past decade, a rich literature emerged focusing on “psychological capital,” a multidimensional concept encompassing self-efficacy, hope, optimism, and resilience. So far psychological capital has been predominantly studied in the areas of work and organizational psychology, management, and organizational behavior. This paper argues that (1) the relevance of psychological capital is much broader than assumed so far and (2) that not only the outcomes but also the (social) origins and sources of psychological capital need to be studied. More specifically, the key questions that we address in this paper concern (1) how the notion of psychological capital can be integrated into a broader capital framework that allows studying (the reproduction of) social inequalities, (2) what such integration adds to disciplines such as psychology and sociology, (3) and which avenues for further research can be derived from such framework? Informed by the work of Pierre Bourdieu, we argue that psychological capital is the missing link to develop a comprehensive framework for studying (the reproduction of) social inequalities. Based on our theory building, we develop an interdisciplinary research agenda.