The commercialisation of scientific knowledge has become a primary objective for universities worldwide. Collaborative research projects are viewed as the key to achieving this objective, however, the role of Principal Investigators (PIs) within these complex multi-stakeholder research projects remains under researched. This paper explores how networks in the scientific knowledge collaboration process are initiated and maintained from a multi-stakeholder perspective. It is based on case study evidence from 82 stakeholders in 17 research collaboration projects in Irish and German universities, which provides for a holistic view of the process, as opposed to prior research which has tended to report findings based on the analysis of one or two stakeholders. It finds that PIs play a lead role in establishing and managing stakeholder networks. This finding is unanimous for all stakeholders, irrespective of research centre size, type and geographical location. Not unlike the entrepreneur, the PI has to be 'a jack of all trades', taking on the roles of project manager, negotiator, resource acquirer as well as, the traditional academic role of Ph.D. supervision and mentoring. The findings suggest that PIs are better placed than Technology Transfer Office managers to act as boundary spanners in bridging the gap between science and industry. © 2012 Springer Science+Business Media New York.