Objective: Models such as family-based treatment (FBT), delivered to both the parent and child, are considered the most efficacious intervention for children with obesity. However, recent research suggests that parent-based treatment (PBT; or parent-only treatment) is noninferior to FBT. The aim of this study was to evaluate the comparative costs of the FBT and PBT models. Methods: A total of 150 children with overweight and obesity and their parents were randomized to one of two 6-month treatment programs (FBT or PBT). Data was collected at baseline, during treatment, and following treatment, and and trial-based analyses of the costs were conducted from a health care sector perspective and a limited societal perspective. Results: Results suggest that PBT, compared with FBT, had lower costs per parent-child dyad from the health care sector perspective (PBT = $2,886; FBT = $3,899) and from a limited societal perspective (PBT = $3,231; FBT = $4,279). Conclusions: These findings suggest that a PBT intervention has lower costs and is noninferior to an FBT intervention for both child and parent weight loss.