Although differential reinforcement is procedurally simple, and a common component in intervention packages for feeding disorders, few published studies evaluated its effects in isolation. Even fewer studies have isolated the effects of differential reinforcement on feeding in free-operant arrangements. In the current clinical case study, we report the expansion of a practitioner's scope of competence to include the treatment of food selectivity by evaluating the effects of differential reinforcement of acceptance with high preferred food in a boy with developmental delays and food selectivity. Acceptance of nonpreferred foods increased first in a restricted operant arrangement, and then a free operant arrangement, both without escape extinction. Improvements in acceptance generalized to additional foods and a parent. These results extend prior research by demonstrating differential reinforcement of acceptance using high preferred foods without escape extinction may improve feeding in restricted- and free-operant arrangements for some children with developmental delays.