Objective: To examine whether cognitive enhancement can be delivered through play to preschoolers with ADHD and whether it would affect severity of ADHD symptoms. Method: Twenty-nine 4- and 5-year-old children and their parents participated in separate group sessions (3-5 children/group). Child groups were introduced games designed to enhance inhibitory control, working memory, attention, visuospatial abilities, planning, and motor skills. Parent groups were encouraged playing these games with their children at least 30 to 45 min/day and taught strategies for scaffolding difficulty levels and dealing with obstacles to daily playing. Results: Parent ratings and session attendance indicated considerable satisfaction with the program. Parent (p < 0.001) and teacher (p = 0.003) ratings on the ADHD-Rating Scale-IV (ADHD-RS-IV) indicated significant improvement in ADHD severity from pre- to post-treatment, which persisted 3 months later. Conclusion: This play-based intervention for preschoolers with ADHD is readily implemented at home. Preliminary evidence suggests efficacy beyond the termination of active treatment.