© 2020, Springer Nature B.V. Objective Structured Clinical Examinations (OSCEs) have become ubiquitous as a form of assessment in medical education but involve substantial resource demands and considerable local variation.A detailed understanding of the processes by which OSCEs are designed and administered could improve feasibility and sustainability. This exploration of OSCE design is informed by Practice Theory, which suggests assessment design processes are dynamic, social and situated activities. The overall purpose is to provide insights that inform on-the-ground OSCE administration. Fifteen interviews were conducted with OSCE academics and administrators from three medical schools in Australia, the United Kingdom and Canada. Drawing from post-qualitative inquiry, Schatzki’s Practice Theory was used both as a sensibility and as an analytic framework. OSCE design was characterised by planning activities, administration activities, negotiation activities and bureaucratic activities; it involves significant and resource-intensive effort in negotiation and coordination. There was considerable local variation but at the same time activities were remarkably consonant across national boundaries. There was a tension between general understandings such as reliability and validity that underpin the OSCE and the improvisational practices associated with design and administration. Our findings highlighted the role of blueprints as a key coordinating artefact but with too many rules and procedures prompting cycles of bureaucracy and complexity. Emphasising coordination rather than standardisation might ease workloads, support adaptation to local environments and prevent an overly reductive approach to this assessment format.