Questions of health care access and equity are often examined by researchers using quantitative approaches, describing patterns of service utilization. Articles based on such approaches often reveal relatively little about how health care services and resources come to be distributed as they are. Articles about qualitative research with marginalized people, although offering textured accounts of people’s experiences of care, often do not systematically link felt troubles to specific features of health systems. Institutional ethnography, a method of inquiry developed over the past 25 years by Canadian sociologist Dorothy Smith and her colleagues, offers a useful resource for researchers exploring and addressing health care disparities. Drawing on previous research and a study in progress on cancer care in Ontario, Canada, I consider the potential of institutional ethnography to make visible how disparities are produced in the routine operation of health services.