Differential outcome and differential response to research-based interventions are challenging issues for researchers, teachers, and families of young children with autism spectrum disorder (ASD). In this article, the authors present information on responders to an early education program, Project DATA (Developmentally Appropriate Treatment for Autism), designed for children with ASD. Using case study methods, the authors identified six themes that were associated with optimal responders. The themes include the following: responders made continual progress, their challenging behaviors served clear functions, teachers were able to identify motivators, responders became sociable, they learned efficiently in group arrangements, and they generalized new skills. Findings are discussed in terms of implications for individualizing intervention approaches within the context of comprehensive treatment models.