Many problems related to information systems implementation are psychological rather than technical. It is necessary to adapt good enough to the current situation in the business to avoid bad user reactions. One of the most important quality factors of an information system is user acceptance. Information system implementation projects have been historically bothered by failures for which user resistance has been identified as an important reason. A poor adaptation of old data may cause user frustration. But the most important problem perhaps is how to deal with the people and know their psychological constraints involved in the system change, their lack of competence And also their reluctance to accept the new system. A poorly designed system interface also becomes an obstacle for the users and they would become more unwilling to tolerate it. This study presents a theoretical and empirical understanding of user acceptance during the implementation of an information system and provides suggestions to an individual and also organizations for tackling such resistance and enhances user satisfaction. / Program: Magisterutbildning i informatik