To ascertain risk factors for the development of overweight in children at 9.5 years of age. This was a prospective study of 150 children from birth to 9.5 years of age, with assessment of multiple hypothesized risk factors drawn from research reports. Five independent risk factors for childhood overweight were found. The strongest was parent overweight, which was mediated by child temperament. The remaining risk factors were low parent concerns about their child's thinness, persistent child tantrums over food, and less sleep time in childhood. Possible mechanisms by which each of these factors influence weight gain are outlined. Two different pathways to childhood overweight/obesity were found, depending on degree of parental overweight. There is evidence of considerable interaction between parent and child characteristics in the development of overweight. Several of the identified risk factors are amenable to intervention possibly leading to the development of early prevention programs.