The concept of open innovation has drawn considerable interest from both researchers and practitioners in recent years. We conceptualize the emerging phenomenon of Open Innovation intermediaries (or ‘Solver Brokerages’) as intermediaries that facilitate innovation exchanges between organizations and crowds. The study presents a theoretical model based on extant research, which is refined through a field study consisting of elite interviewing, with representatives from four solver brokerages as well as stakeholders from an innovation-seeking organisation and a solution provider. In exploring how Solver Brokerages enhance knowledge mobility, the paper examines the ways in which providing access to a knowledgeable and diverse solution community, facilitating problem decomposition and articulation, and mechanisms for increasing appropriability affect knowledge mobility. In addition, the paper examines the ways in which filters and rewards affect appropriability as well as the roles played by collaborative mechanisms in mediating these effects.