Abstract
Inter-organizational projects, understood as project groups involving multiple organizations that come together to achieve a common goal with a clear deadline, often face complexities related to the involvement and influence of multiple (social) system levels. These system levels provide references in the form of norms, values and standard behaviors that project actors apply during project activities. A lack of understanding of these norms has been shown to lead to distrust and other problems during collaboration. This is especially problematic when one considers taboos. Unspoken and unwritten, taboos are a specific type of social norms that indicate that which is forbidden or prohibited. Using an ethnographic research approach with action research elements, this study will focus on a circular renovation project involving actors from the client, the contractor, and several sub-contractors.