Evidence-based practice, or evidence-based decision-making, is rapidly developing as a growth industry in nursing and the health professions more widely. It has its origins in the work of the British epidemiologist Archie Cochrane and has recently been re-energized in Canada by the National Forum on Health and its call for a culture of evidence-based decision-making. Before we adopt evidence-based nursing (EBN) as a mantra for the 21st century, we should examine its origins and its consequences, and we should probe related concepts, 2 of which are the nature and structure of practice-based knowledge and the nature and structure of evidence generally. Findings of a recent survey of nurses in western Canada are used to illustrate that nurses use a broad range of practice knowledge, much of which is experientially based rather than research-based.