Advances in the understanding of our world require us to recognize underlying structure - structure that is often hidden from direct view. Recognizing this structure may depend on the development of better methods of observation. Galileo's construction of the telescope and subsequent advances in electronic measuring devices contributed to the recognition of fundamental physical principles and advances in our understanding of the physical world. Similarly, measures of adherence have evolved that permit us to recognize human behavioral processes, which are often hidden from direct observation. Questionnaires, pill counting, and weighing medications reveal that patients may be noncompliant. These measures, however, clearly overestimate patients' true adherence. New objective electronic measures demonstrate that noncompliance is even more pervasive than previously estimated and give us insight into underlying dynamic processes with broad implications for dermatology. 28 There is a growing awareness of the prevalence and importance of adherence in dermatology.7,17,29-34 We are on the verge of understanding that patient noncompliance is a nearly universal principle of dermatologic treatment. Recognizing that nonadherence is ubiquitous is essential for understanding many dermatologic phenomena and for addressing many of the recalcitrant skin disease dilemmas seen in dermatology. All long-term trials in dermatology should have measures of compliance built into their design. Equally important, physicians must develop practical measures to improve patients' compliance behavior: establishing a strong, trusting physician patient relationship; choosing vehicles that can fit patients' lifestyles; using patient education materials designed to motivate without overly stressing risks; and scheduling a follow-up visit shortly after initiating a new treatment. 29 Physician-administered treatments that assure adherence (such as intralesional corticosteroid injections and, as described by Soares and Davis35 in this issue, Goeckerman treatment) have important advantages and will always find useful application. By addressing adherence, we can achieve better success for patients with psoriasis and other chronic skin diseases. ©2007 American Medical Association. All rights reserved.