Childhood obesity is among the most difficult problems that confront pediatricians. Its rising prevalence and its increasingly recognized risk of morbidity heightens our concern and increases our frustration when families appear unmotivated or when treatment fails. Because childhood obesity is so difficult to treat and because obesity is viewed widely as a form of social deviancy, we are tempted to blame patients and families for our lack of successful therapy. In this review we consider the identification of childhood obesity, explore its potential etiologies and consequences, and outline an approach to therapy. Identification The identification of childhood obesity and its severity clarifies the degree of risk and represents the first step of therapy. The two indices used most commonly to determine the degree of adiposity in humans are the body mass index (BMI, weight in kg/height in m2) and the triceps skinfold thickness. Each has advantages and limitations. The advantage of the BMI is that height and weight are measured easily and reliably in a variety of settings by personnel who have had minimal training. A BMI in excess of the 85th percentile has been used arbitrarily to define obesity. However, the BMI does not measure fatness directly. Variations in frame size as well as increases in fatness will increase the BMI.