This paper identifies different university spin-off (USO) roles related to resource interaction among business parties. It does so by mapping how USOs become part of business networks in terms of their roles relative to other parties. The theoretical frame of reference focuses on roles and resource interaction based on an industrial network approach to business markets. The empirical research is based onfive cases of USOs representing a variety in terms of technology, degree of newness, sector, and area of application. As a result of the analysis, three different roles are identified: the USO as resource mediator, resource re-combiner and resource renewer. These roles reflect how USOs adapt resources to, or require changes among, business parties' resources. The paper also discusses the main resource interfaces associated with the three roles and related challenges. The paper contributes to previous research through illustrating USOs' roles relative to business parties from a resource interaction point of view, and by pointing to the establishment of new companies in business networks as a way of implementing innovation. Finally, the paper discusses the managerial implications of the research in terms of the USO's need to understand which role to take and how to develop it.