This study evaluated primary care providers' (PCPs, pediatricians, and nurse practitioners) knowledge, current practices, and perceived barriers to childhood obesity prevention and treatment, with an emphasis on first-year well-child care visits. A questionnaire was distributed to 192 PCPs in the primary care network at The Children's Hospital of Philadelphia (CHOP) addressing (i) knowledge of obesity and American Academy of Pediatrics (AAP) guidelines, (ii) anticipatory guidance practices at well visits regarding nutrition and exercise, and (iii) perceived barriers to childhood obesity treatment and prevention. Eighty pediatricians and seven nurse practitioners responded, and a minority correctly identified the definition (26%) and prevalence (9%) of childhood overweight and AAP guidelines for exercise (39%) and juice consumption (44%). Most PCPs (81%) spent 11-20 min per well visit during the first 2 years, and 79% discussed diet, nutrition, and exercise for > or =3 min. Although >95% of PCPs discussed juice, fruits and vegetables, sippy cups, and finger foods during the first year, over 35% never discussed fast food, TV, or candy, and 55% never discussed exercise. Few rated current resources as adequate to treat or prevent childhood obesity. Over 90% rated the following barriers for obesity prevention and treatment as important or very important: parent is not motivated, child is not motivated, parents are overweight, families often have fast food, watch too much TV, and do not get enough exercise. In conclusion, there is much room to improve PCPs' knowledge of obesity and AAP guidelines. Although PCPs rate fast-food consumption, TV viewing, and lack of exercise as important treatment barriers, many never discussed these topics during the first year.