Individuals diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD) present with a wide array of cognitive and behavioral deficiencies. Over the past few decades, researchers have proposed a variety of theoretical models to account for and to better characterize this highly heterogeneous disorder. This paper reviews the recent literature on the neural and neurocognitive determinants of ADHD and emphasizes the importance of conceptualizing the disorder within a developmental framework. Implications for treatment are discussed.