Evidence-based medicine is an approach to clinical practice and teaching that emphasizes decision-making based on rigorous analysis of clinical research tailored to the individual characteristics of a specific patient. As such, it can be considered the scientifically grounded art of medicine. Through evidence-based guidelines, pathways, and algorithms, the care of populations of patients may also be facilitated by informing individual practitioners of optimal decision-making in specific situations or providing the foundation for comprehensive "disease management" programs. These programs coordinate care for patients with chronic conditions, such as rheumatoid arthritis and osteoarthritis, across time and multiple disciplines. We present an approach to the development of decision-making aids, including guidelines and algorithms, which should be helpful in the care of individual patients and populations for whom physicians and other healthcare practitioners are responsible.