Thispaperexaminesphysicians’progressnotes,anartifactthat,inspite of its obvious importance in the coordination of cooperative work in clinical set- tings, has not been subjected to systematic study under CSCW auspices. While several studies have addressed the role of the medical record in patient care, they have not dealt specifically with the role, structure, and content of the progress notes. As a consequence, CSCW research has not yet taken fully into account the fact that progress notes are coordinative artifacts of a rather special kind, an open-ended chain of prose texts, written sequentially by cooperating physicians for their own use as well as for that of their colleagues. We argue that progress notes are the core of the medical record, in that they marshal and summarize the overwhelming amount of data that is available in the modern hospital environment, and that their narrative format is uniquely adequate for the pivotal epistemic aspect of coopera- tive clinical work: the narrative format enables physicians to not only record ‘facts’ but also—by filtering, interpreting, organizing, and qualifying information—to make sense and act concertedly under conditions of uncertainty and contingency.