Individual academic scientists engage in various collaborations through their involvement in both regional and extra-regional networks. However, little is known about how these networks are actually formed. Focusing on university and industry networks, we take the view that the process of building new networks is an entrepreneurial activity that involves unpredictability and often goal ambiguity. This paper thus employs the theories of causation and effectuation to explore how the personal networks of academics are initiated. With evidence from the networks of 12 academics based at the University of Stavanger, Norway we show that both causation and effectuation are employed by academics when building their networks. The usage of causation was found to be more consistent with building industry networks whereas effectuation was employed when building networks in academia. Consequently, effectuation was characteristic of the international networks which were found to be mostly constituted by other academics. On the regional level, a mixture of both approaches of causation and effectuation was observed, with more industry linkages suggesting a tendency to be more causal than effectual. Furthermore, while causation was employed for project level networking, effectuation was employed for establishing more individual level ties.