This paper examines the concept of open innovation within the context of corporate social responsibility. It demonstrates how the practice of open innovation unfolds in inter-organizational collaborations that involve the voluntary or charitable sector, outlining the findings of an explorative collective case study of eight voluntary dyadic partnerships between corporate and nonprofit organizations in the United Kingdom, which have resulted in innovation outcomes. Two generic approaches to open innovation were witnessed: firstly, a more exploratory approach to dyadic engagement activities that resulted in an emergent innovation process, and secondly, a focused and pre-determined search activity to exploit the resources of the nonprofit partner that demonstrated a more planned innovation process. Two distinct boundary-spanning roles were identified: in dyads exhibiting few organizational linkages, the role was associated with formal responsibilities from senior management to 'manage' innovation opportunities and outcomes. In dyads exhibiting high linkages, there was no such formality; the role was a 'conduit' to facilitate search and exploration to locate opportunities for innovation through idea exchange. Overall, this research demonstrates the value of an open innovation approach driven by the need to address societal and social issues (rather than those purely economic). Such practice broadens a firm's 'search' activities and delivers innovations in exchange for enhanced social legitimacy - acting innovation capital for future enterprising activities and market advantage.