Social capital – as reflected in inter-organizational network relations – is a widely researched phenomenon for large, mostly publicly listed firms. With respect to social enterprises, however, little is known about the importance of social capital. We aim at closing this gap by empirically analyzing the influence of various dimensions of social capital on knowledge transfer, social innovation, and, subsequently, social impact. We theorize that social capital is positively related to social innovation with knowledge transfer also acting as partial mediator. Furthermore, we suggest that social innovations are positively related to the social impact of these firms. Based on a large sample of social enterprises, the results of fitting these to a structural equation model provide broad support for these considerations.