Purpose: To compare the costs of parent-only and family-based group interventions for childhood obesity delivered through Cooperative Extension Services in rural communities. Methods: Ninety-three overweight or obese children (aged 8 to 14 years) and their parent(s) participated in this randomized controlled trial, which included a 4-month intervention and 6-month follow-up. Families were randomized to either a behavioral family-based intervention (n = 33), a behavioral parent-only intervention (n = 34), or a waitlist control condition (n = 26). Only program costs data for the parent-only and family-based programs are reported here (n = 67). Assessments were completed at baseline, post-treatment (month 4) and follow-up (month 10). The primary outcome measures were total program costs and cost per child for the parent-only and family interventions. Findings: Twenty-six families in the parent-only intervention and 24 families in the family intervention completed all 3 assessments. As reported previously, both intervention programs led to significantly greater decreases in weight status relative to the control condition at month 10 follow-up. There was no significant difference in weight status change between the parent-only and family interventions. Total program costs for the parent-only and family interventions were $13,546 and $20,928, respectively. Total cost per child for the parent-only and family interventions were $521 and $872, respectively. Conclusions: Parent-only interventions may be a cost-effective alternative treatment for pediatric obesity, especially for families in medically underserved settings.