Attention deficit hyperactivity disorder (ADHD) is a childhood-onset disorder that is considered one of the most common neurobehavioral disorders. The symptoms of ADHD should be cast, not as static or fixed neurobehavioral deficits, but rather in terms of underlying developmental processes. Targeting attentional disorders early in life can bring about fundamental alterations in the pathogenesis of ADHD, and thus prevent or moderate the course of the disorder. The developmental approach can enable predictions concerning characteristics of ADHD that develop over time and inform us about multiple risk and protective factors that transact to impact its development, as well as the development of a broad range of associated co-morbid features. In this review, we describe the complex factors that predict and mediate the developmental course of ADHD, providing early cues for ADHD diagnosis and intervention in young children that will optimize outcome.