In recent decades, policy makers and researchers have taken an increased interest in university spin-offs. Entrepreneurship research provides limited knowledge of the role of the social network actors of external entrepreneurs in the formation process of university spin-offs. External entrepreneurs, who come from outside the university, are likely to use other network actors than academic researchers. This may influence the subsequent development of the firm. The purpose is to develop a conceptual framework for the role of social network actors in the formation of university spin-offs managed by external and inventor entrepreneurs. Literature of social networking, university spin-off formation and external and inventor entrepreneurs guide this study. This study employs a case study design that contains three external and three inventor entrepreneurs of Swedish university spin-offs. The results demonstrate that business actors, support actors and technology actors influence the firm formation process. The study also shows that external entrepreneurs have strong ties (direct access) to business actors while inventor entrepreneurs have weak ties (indirect access) to business actors via the university incubator. University incubators are less important for external entrepreneurs than inventor entrepreneurs because of their strong ties to business actors. The chapter provides implications for researchers and policy makers. © 2017 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.