The purpose of this paper is to study how communication enables knowledge integration within transnational projects. Using longitudinal case study data to explore the theoretical arguments, interesting findings emerge. The main finding is that knowledge integration within the transnational project was hampered by ignorance – among project managers and members – of the impact and link between the use of different communication tools, subsequent communication process and knowledge integration. Other findings relate to how institutionalised behaviour persist change and subsequently partly explained why the communication process and thereto related communication tools were not adjusted to new circumstances and conditions. Finally, communication is an inherent part of knowledge integration within a transnational project and there is a need for communication to be sensitive to the complexity of the knowledge being integrated.