It has long been recognized that many individuals with ADHD also have difficulties with emotion regulation but lack of consensus on how to conceptualize this clinically challenging domain renders a review timely. The authors examine the current literature using both quantitative and qualitative methods. Three key findings emerge. First, emotion dysregulation is prevalent in ADHD throughout the lifespan and is a major contributor to impairment. Second, emotion dysregulation in ADHD may arise from deficits in orienting towards, recognizing and/or allocating attention to emotional stimuli; these deficits that implicate dysfunction within a striatoamygdalo-medial prefrontal cortical network. Third, while current treatments for ADHD often also ameliorate emotion dysregulation, a focus on this combination of symptoms reframes clinical questions and could stimulate novel therapeutic approaches. Three models to explain the overlap between emotion dysregulation and ADHD are considered: emotion dysregulation and ADHD are correlated but distinct dimensions; emotion dysregulation is a core, diagnostic feature of ADHD; and the combination constitutes a nosological entity, distinct from both ADHD and emotion dysreguation alone. The differing predictions from each model can guide future research into this much-neglected population.