ABSTRACT. Objective. Because of the rising rates of childhood obesity, we set out to determine what is known about its causes and what could be done to prevent additional increases.Methodology. A meeting was convened of experts in areas that bear on prevention of obesity development during intrauterine life, infancy, and very early childhood. They presented recent data and their interpretations of the stage of our current knowledge in related areas. They also proposed possible useful interventions and future directions for research.Findings. The speakers' talks indicated that (1) breastfeeding as currently practiced seems to be significantly (albeit weakly) protective against obesity and should be encouraged as the preferred method of feeding infants for as long a duration as practical during the first year of life; (2) infant-feeding practices are changing in a way that may predispose to obesity (eg, soda and french fries are being fed to infants as young as 7 months of age), possibly altering taste preferences for foods and beverages that are energy dense and nutrient poor; (3) although little is known about parenting styles (eg, authoritative versus permissive), parenting style is likely to be a fruitful area of current research into childhood obesity etiology; and (4) the pattern of weight changes in the first few years of life may contribute to later risk of obesity.Conclusions. Children's obesity will continue to be a growing problem unless we improve understanding of the key factors likely to be operative during intrauterine life, infancy, and very early childhood, identify those in whom intervention would have the greatest effect, design and evaluate preventive interventions, and promote those that are successful.