A generation ago the nineteenth century was at the heart of medical historical scholarship, as the era when modem medicine was born. Over the last decade or so things have changed: other centuries vie for center stage, and former key "turning points," like hospital medicine and laboratory medicine, are now seen in terms of continuities on longer timescales. But though chronologically reframed, the modes of medicine still appear chiefly at the level of programmatic intentions, including rhetorical uses of science. This essay argues that work in this vein needs to be complemented with equal attention to the performative aspects of practice--in the clinic, in the laboratory, and in the field--and that historians of medicine still have much to learn from the "practice turn" in the history of science.