In this chapter, obstacles and enablers for the implementation of sustainable project management are identified. Focus is given to the missing link between formulation of the sustainability strategy-corporate sustainable ambitions and vision-and the implementation on project level. Focussing on a large engineering company, the factors affecting the implementation of sustainability on six projects are studied. This exploratory empirical study suggests that the clients largely determine the level of sustainability and that there is a gap between ambitions and intentions of the engineering company and actual implementation. A more pro-active approach of the engineering company revolves around the alignment of sustainability ambitions with the client, the explicit discussion of sustainability in the company and in project teams to stimulate a sustainability mind-set and show casing earlier sustainability achievements. A framework is provided giving sustainability a more central role in the practice of the engineering company.