This is the second edition of a book originally published in 1988 as part of the series Critical Issues in Neuropsychology. The editors describe it as expanding the content and updating the rapidly growing literature on the relationship between cognition and systemic (nonneurological) disease. Although most of the chapter titles remain the same, some of the authors are new. Some of the chapters from the first edition, including those on childhood nutritional disorders and on cancer, have been dropped. New additions include chapters titled “Autoimmune Disorders,” “Sleep Disorders,” and “Neurobehavioral Complications of HIV Infection.” While the contents of the book remain clearly focused on the effects of systemic illness on cognition, some chapters, such as the one devoted to neurobehavioral complications of HIV infection, discuss cognitive impairment secondary to presumed primary central nervous system diseases. However, with evolving knowledge of the pathophysiology of HIV-related cognitive impairment, systemic factors are also increasingly being recognized.