Physicians in community-based practice rarely have the time, nor the inclination, to participate in formal, controlled clinical research. While few would question the importance of statistically valid clinical trials focused on establishing the safety and efficacy of new pharmaceuticals and medical devices, most busy practitioners recognize that formal clinical research can't be approached casually. Beyond the operational infrastructure typically required to execute medical research, the imposition of fundamentally experimental research is such that it is not easily accommodated in day-to-day medical practice. Indeed, the often artificial nature of controlled clinical research is, in many ways, incompatible with actual practice conditions. However, the characteristics and, more importantly, the outcomes of "real world" medical practice are becoming of increasing scientific and practical importance. Underscored by recent post-approval drug recalls, the "real world" practice environment can be an invaluable source of information on the actual effectiveness of treatment regimens, drugs, and devices. Inasmuch as clinical trials tend to exclude noncompliant patients and those with comorbid conditions, a new paradigm is appropriate for capturing the outcomes of actual practice. While not without statistical and analytical limitation, the brand of "naturalistic" research undertaken in observational patient registries is becoming rapidly accepted by both the scientific and practitioner communities.