In this article we describe the nature of attention deficit disorders (ADDs) within an individual differences model of abilities. In so doing, a model-based explanation for the sources of learning and performance difficulties among individuals identified with ADDs is provided. Earlier models of ADDs are discussed, and the proposed loci of ADDs according to each model are delineated. The explanatory advantages of the model advanced in this article, compared to previous models, are discussed. The individual differences delineated in the model can be harnessed fruitfully with consequent improvements in the individual's adaptive behaviors and school performance.