Young adults with substance use disorder (SUD) commonly experience co-occurring emotional distress in the form of affective/emotional disorders (i.e. anxiety, depressive, and related disorders) and self-injurious thoughts and behaviors (SITBs). Based on the conceptualization of emotion dysregulation as a transdiagnostic treatment target, the current study utilizes the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP) to target core psychopathological processes related to emotion dysregulation that underlie SITBs and emotional disorder pathology. Given its transdiagnostic format, the UP has the potential to address comorbidity among the emotional disorders (and other functionally similar problems such as SUDs) simultaneously and more comprehensively than single-diagnosis treatments.