In this article we develop a theoretical perspective of how professional identities in multi-professional organisational settings are co-constructed in daily interactions. The research reported here is located in a healthcare context where overlapping knowledge bases, unclear divisions of responsibilities, and an increased managerialist emphasis on teamwork make interprofessional boundaries in healthcare opera- tions more complex and blurred than ever. We thereby build on a research tradition that recognises the healthcare sector as a negotiated order, specifically studying how professional identities are invoked, constructed, and re-constructed in everyday work interactions. The perspective is employed in an analysis of qualitative data from interviews and participant observation at a large Swedish hospital, in which we find three main processes in the construction of space of action: hierarchical, inclusive, and pseudo-inclu- sive. In most of the interactions, existing inter-professional divides and power relations are sustained, pre- venting developments towards integrated interprofessional teamwork.