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 operations 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-inclusive. In most of the interactions, existing inter-professional divides and power relations are sustained, preventing developments towards integrated interprofessional teamwork.