In information system (IS) acquisition, one of the major challenges is to carry out required changes in the organization. One major problem is the lack of organizational support, user participation and competence. The process of gaining organizational support has been presented as the legitimation process. The legitimation process includes the actions taken by a legitimation seeker to gain legitimation from legitimation providers. In IS acquisition, the individuals’ behavioural patterns can be perceived as representing specific roles. Published studies combining these roles and actors in the legitimation process in IS acquisition are rare. Consequently, we will explore the roles in the IS acquisition legitimation process in two cases. As a result, we illustrate how legitimation appears in practice and provide a deeper understanding of how different roles act in legitimating IS acquisitions.