Obesity in children is a problem both insidious and acute. Childhood obesity has been indicated as a forerunner of adult obesity; it is also an immediate problem for the child. Given the lack of evidence for long term maintenance of any weight loss, this paper investigates the etiology of the disorder as a prelude to prevention. Upon review of the psychological, pediatric, and nutritional literature, it was found that obesity in infancy or childhood does not predestine obesity in adulthood. However, there is a channeling tendency apparent from infancy that increases with age. Further, there is no current evidence to support any one theory (e.g., genetic, social learning) or mechanism (e.g., lower metabolism, overeating) as the cause of juvenile obesity. Findings in these areas are reviewed, and methodological flaws and disagreements hindering further understanding are cited. Finally, the discussion offers some preventive measures for subsequent investigation. (Author/RH)