In older adults, many negative health events occur not because cures for diseases are not available or because proper treatment was not applied, but because patients fail to follow the medical instructions or regimens that were essential to maintain their health. Increasingly, it is becoming recognized that many negative health outcomes result from difficulty in following or understanding medical instructions, or from an unwillingness to follow instructions. In Medical Adherence and Aging, prominent psychologists and geriatricians examine the research on nonadherence using a cognitive, social, and developmental framework focusing particularly on the problems of adherence in older adults.