In the United States, 40 to 45% of those over 60 years of age have the metabolic syndrome (1,2,3), and this percentage, based on estimates of the increasing prevalence ofexcess body weight and the more comprehensive diagnostic criteria for the syndrome, is likely to exceed 60% in newer survey analyses. Children and adolescents, too, are being affected by the metabolic syndrome, in parallel with the increasing prevalence of overweight in young people, now estimated to include 16% of those age 6 to 19 years. Clinicians see with increasing frequency that routine office visits demonstrate the meta­ bolic syndrome, a constellation of discrete but closely related metabolic disturbances indicative of increased risk for (or presence of) cardiovascular disease and/or diabetes. All estimates suggest the increasing impactof the metabolic syndrome on mortality and morbidity (4). Our aim in developing this new synthesis and analysis of the metabolic syndrome has been to bring together the viewpoints of the epidemiologists, the physiologists, the molecular biologists/biochemists, and the clinicians toward understanding the current state ofknowledge ofboth the causes and the consequences of the metabolic syndrome. These writers aim to stimulate new thinking concerning underlying mechanisms and to encourage heightened efforts to develop new therapeutics, potentially targeting uniquely intersecting pathways or points of intervention. This book is an extended call to action to slow or halt the rising tide of the metabolic syndrome (5).