Health services research is a field that uses techniques from many other disciplines to study health care, especially its quality and costs. This article presents examples that illustrate how health services research addresses the delivery of dermatologic care-for example, the development and use of sound quantitative measures of the outcomes of our care, the implementation of strategies to improve these outcomes, the assessment of patients' access to care and their satisfaction with care, and determinations of the cost-effectiveness of our care. Following these examples is a brief review of principles of experimental inquiry and common methodologic pitfalls in health services research, as a guide for readers in the interpretation of published studies.