This review considers a variety of perspectives on overweight and obesity (OW/obesity), including measurement and classification; prevalence and changes in prevalence in recent years; genetic, biological, medical, individual, and social correlates of OW/obesity; and treatment approaches. Despite increased attention, OW/obesity is escalating in prevalence worldwide, and the causes are exceedingly complex. A range of innovative studies, including basic research on gut microflora, dietary composition, pharmacologic interventions, and surgical procedures, is generating findings with potential for future prevention and treatment of OW/obesity. Social system changes such as school programs and the awareness of the roles of personal, family, health provider, and cultural experiences related to OW/obesity have also gained traction for vital prevention and treatment efforts over the past decade.