This article discusses a number of issues related to the diagnosis and treatment of children with attention-deficit hyperactivity disorder (ADHD), with specific implications for preschoolers. A brief review of diagnostic and treatment issues for young children is followed by a discussion of developmental issues that contextualize the preschool years and have an impact on cognitive and emotional development underlying self-regulation. The characteristics of the high numbers of children with ADHD receiving services within community-based systems of care and symptom outcomes are reported, as well as a description of the components of the systems of care approach. Recent federal initiatives that impact the care of children with ADHD within community settings are highlighted. It is concluded that the identification and management of preschool children with ADHD can be effective within the context of fully integrated service system approaches.