Decades of research support 3 interventions for youth with attention-deficit/hyperactivity disorder (ADHD): behavioral intervention, stimulant medication, and their combination. However, professional organizations have long disagreed regarding the best approach for implementing evidence-based interventions for ADHD in practice. The accompanying Society of Developmental and Behavioral Pediatrics guidelines for complex ADHD provide a framework for initiating treatment with behavioral intervention and adding stimulant medication as necessary, resulting in combined/multimodal treatment for many, if not most, children. In this special article, we review the extant literature on combined treatment, with special emphasis on the past 15 years of research that have led to the recommendation for this approach. Specifically, we review the literature on dosing and sequencing of multimodal treatment for youth with ADHD and the impact of multimodal interventions on areas of functional impairment. The extant research provides clear support for a psychosocial-first approach in treating youth with complex ADHD.