This paper provides a summary of the current conceptualization of what AD/HD is, and its etiology, and then reviews some of the recent literature on the correlates and lifecourse outcomes for individuals diagnosed with Attention-Deficit/Hyperactivity Disorder (AD/HD). The intention is to synthesize that which is known, and to identify important gaps in the literature and knowledge base, which secondary analysis of prospective large-scale longitudinal cohorts, tracking individuals from birth to adulthood, could help to fill. This review highlights the fact that such datasets are rare and that their analysis offers important opportunities for advancing knowledge, particularly of the adult outcomes of childhood AD/HD.