Psychosis spectrum disorders (PSDs) are complex, highly heritable psychiatric conditions with high economic and societal costs. PSDs have historically been conceptualized as neurocognitive disorders in which psychotic episodes and impairments in social and emotional functioning are attributed to deficits in neurocognition. Although cognitive pathways play an important role in the etiology and presentation of PSDs, recent research suggests that interrelations between cognition and emotion are highly relevant. Moreover, aberrant emotion regulation likely plays a significant role in the presentation of PSDs. Emotion dysregulation (ED) may underlie and exacerbate both negative and positive symptoms in PSDs, such as blunted affect, avolition, disorganized speech and behavior, poor social cognition, and delusions and hallucinations. Advances in measurement of emotion dysregulation—including self-reports, behavioral paradigms, neuroimaging paradigms, and neurophysiological assessment—have informed etiological models of emotion dysregulation in PSDs. This chapter reviews research on emotion regulation and dysregulation in PSDs. Notably, more severe presentations of emotion symptoms and greater emotion regulation impairments are associated with worse outcomes in PSDs. It may therefore be the case that focusing on ED as an early risk factor and intervention target could improve outcomes and prevention approaches for psychotic disorders.