The task of integrating a complete EPR in large, complex divisionalized organizations that rely on highly professional works such as doctors and nurses presents a particularly difficult challenge. Much more is needed to be known, particularly in terms of organizational factors. My theoretical motivation in conducting this research evolves upon the interests of studying perspectives on organizational change and the role of human agency in determining the performance of an in-house developed portal system during its gradual integration in a large and complex hospital in Norway. Boudreau and Robey (2005) discusses that “a human agency position suggests that human are relatively free to enact technologies on different ways”. In this thesis, the transformation from why the participants choose not to use the system (inertia) develops a new practice that leads into an unofficial division of labour (reinvention). It is called improvised learning when the users have acquired knowledge of the clinical portal in ways that were neither planned nor anticipated (Orlikowski 2000). It is the transition between the enactment of inertia and reinvention. Engeström’s (1999) basic structural model of activity represents the mutual relationship between the subject, its community and the object. These three given entities are mediated by several factors that will influence the development of an outcome. Based on this model, I was motivated to illustrate the when, why and how of the clinical portal’s usage. To generate a deeper understanding of the activities evolving around the work practices of the clinical portals’ users, I chose structural model of activity to analyze and define the processes which surround the clinical portal.