Introducing new Information Systems (IS) to organizations often brings changes to the status quo and IS managers need to gain acceptance and support from stakeholders. Legitimation is an abstraction of formal and informal approval of stakeholders toward organizational activities. Our research motivation is to demonstrate that a process-based understanding of legitimation-seeking activities is important for understanding how IS are legitimated in organizations, and to suggest that the area of legitimation presents a potentially valuable framework for IS research by drawing together previous studies concerning problems such as acceptance and resistance, user involvement and participation. We investigate the legitimation seeking process in an IS project at a large Chinese organization, employing a qualitative approach and a case study method. Findings from our case study show that achieving legitimation is important in successfully developing and implementing IS. This paper suggests that activities for gaining, maintaining and repairing legitimation should be considered and carried out in an integrated way, and a new Integrated Legitimation Activity Model (ILAM) is proposed. The paper also discusses the two different legitimation seeking approaches (conformity and manipulation) adopted by the project team, and analyses factors that influenced the project team’s choice of these approaches. Limitations and directions for further research are discussed.