This study investigated the effects of naturalistic, teacher-mediated intervention strategies on increasing levels of active engagement in young children with developmental delays. All interventions occurred in the context of ongoing child-selected play activities in inclusive preschool classrooms that used developmentally appropriate practices. Results showed that the intervention strategies were effective in increasing the level of active engagement in identified areas of need for all three children. Additional data on classroom ecological factors suggest that classroom social and ecological characteristics important to developmentally appropriate practices were maintained during intervention sessions. Checklists on the acceptability of the intervention to classroom teachers and parents are discussed.