Organizations have spent and continue to spend millions of dollars on information systems (IS) in order to enable business success. Information systems have long been used to help managers make better decisions, better understand the nature of customers and improve employee productivity. They have enabled transformations in organizations, such as simplification and acceleration of work processes, and contributed to continued improvement and innovation in these processes. It is not that easy however to make this simplification and acceleration of work processes to happen. A common problem is that individuals that are supposed to use these systems do not use them, and if an information system is to contribute to business success it has to be adopted and used. The question is therefore, how do we get individuals to adopt and use systems that are implemented? This dissertation focus on what influences individual adoption and use, and how we can get individuals to adopt and use systems that are implemented. The information system under investigation is an electronic ordering (e-ordering) system. E-ordering systems are used by individual end-users (requestors, authorizers and goods receivers) in an organization when ordering products and services. The system aims at contributing to reduced maverick (i.e. wild) purchases and increased compliance with a few centrally chosen suppliers, thus facilitating lower purchasing prices and a reduction of the costs for purchasing. The thesis also discusses the relative difficulty in getting individuals to continue to use the system compared to get them to adopt it. Another issue that is discussed is that the acceptance process does not have to happen gradually, it can instead happen in short spurts. It is further discussed what can influence these spurts. / Diss. Stockholm : Handelshögskolan, 2009 Sammanfattning jämte 5 uppsatser