This master thesis aims to give a deep insight into the commercialisation process of Norwegian technolgy transfer offices (TTOs) and how inventors are involved in this process. We also aim to point out what affects the extent of inventor involvement in the commercialisation process of TTOs and how inventor involvement affects the output of TTOs. We conducted a multiple embedded case study on the four largest Norwegian TTOs. Our data is based on interviews with inventors, entrepreneurs and TTO managers. We also enriched the data in one of the cases with participant observations from a six months entrepreneur-in-residence program in one of the TTOs. With this study, we aim to enlighten the aspect inventor involvement since it has received little attention so far among academic entrepreneurship scholars. Our findings reveal that even though TTOs follow a predetermined commercialisation process, it is not rigorously followed. We further identified that knowledge of the TTO staff, monetary aspects, academic recognition and a higher feasability for an invention coming into use are all factors that motivates an inventor to participate in the commercialisation process. Our study reveals that inventor involvement has a positive effect on the output of Norwegian TTOs. Our results are consistent with prior scientific literature and derived from knowledge-based theory to discuss the phenomenon inventor involvement in the setting of university based technolgy transfer.