This doctoral thesis describes three case studies of service engineers participating in organizational change, interacting with managers and consultants. The study investigates the role of differences in professional discourse and culture when these three professional groups interact in organizational change, and how this affects the change result. We bring together two scientific fields, first change management and second, linguistics. The intersection represents the overlapping field of professional discourse and culture. The research design was an explorative multiple case study using qualitative linguistic analyses. The study found that successful organizational change is the result of interaction between professional culture, the organizational culture and the organization/change context. The differences between the professional cultures and discourses can hamper the change process. The practical contribution of this study might be the increased awareness among professionals about their own professional, and often implicit, assumptions. Managers, consultants and service engineers have to be aware of the group dynamics and the specific role of their own typical professional discourse and culture in a change project setting.