The Unified Process has become a widely known and used framework for software development organizations. The use of the framework, however, is not straight forward, and it has not been the intention from the creators of the framework that the development organization should use it ?out of the box?. Some sort of tailoring or adoption is therefore necessary. This paper describes and investigates a case of tailoring, introducing and using RUP in a large software organization. The findings indicate that sufficient knowledge and motivation is an important factor of adopting a methodology.