The current study examines the efficacy of two treatments to help children with cystic fibrosis (CF) meet their dietary calorie requirements of 120% to 150% of the recommended daily allowance of energy and the effect of these treatments on weight gain and maintenance. One treatment provides children with CF and their parents nutrition education about the best foods for meeting their dietary needs. The second treatment gives children with CF and their families similar nutritional information plus behavioral parenting methods for motivating children to eat the recommended foods. Children with CF and their families are seen weekly for 7 treatment sessions across 9 weeks for the active phase of treatment. Families are then followed for 2 years after treatment in order to better understand how long the treatments are effective and to determine the health benefits of better nutrition status and weight gain.