Project management handbooks and courses teach structured and standardized ways of organizing and managing projects, including clearly defined project roles. However, projects are no isolated islands and projects in practice continuously develop and change. This is the case in, for example, the project based construction industry, and in which new inter organizational and collaborative work practices have become increasingly common. This paper is based on two case studies and explores developments and changes in construction project practice, in particular the development of new roles. The concept of liminality is used as analytical lens to better understand these new roles. Findings show new and challenging multi liminal roles that origin from other knowledge domains and professional communities of practice, than what is traditional in construction project management. This development poses both opportunities and challenges for the individual project worker and the development of construction industry practices.