As a consequence of ongoing urbanisation, construction projects are likely to be performed in multi-project contexts. Zooming out from the single project and focussing on the context in which construction projects are performed is suggested as a way to broaden our understanding and develop new theory. The empirical case in focus here, which is studied as a project ecology, is the development of a major urban development district, where several interdependent construction projects have been initiated in sequence and in parallel in a limited geographical area. This case poses several challenges to the developers (construction clients) who are performing their projects simultaneously, and literally, as neighbours. Therefore, we zoom out from the single construction project and put the project in a wider context on a macro level, to increase the understanding of the context in which construction projects are performed. The theoretical lens of social capital helps us zoom in on the interdependencies that develop over time, going beyond traditional, contractual and vertical relationships. Based on empirical material, including interviews and meeting observations, the findings indicate that the developers have to coordinate horizontal interdependencies between projects. The findings also show that the construction client’s role has been extended from initiating and delivering the project mission to also having a collaborator role between projects, where ambidexterity is required.