This study examined associations among childhood abuse, emotion dysregulation, and probable posttraumatic stress disorder (PTSD) within a sample of 93 substance use disorder (SUD) patients in residential treatment. SUD patients with probable PTSD (vs. non-PTSD) reported (a) greater severity of childhood sexual, physical, and emotional abuse and (b) significantly higher levels of overall emotion dysregulation and the specific dimensions of difficulties engaging in goal-directed behavior when upset, difficulties controlling impulsive behaviors when distressed, limited access to effective emotion regulation strategies, and lack of emotional clarity. Additionally, significant positive associations were found between both childhood physical and emotional (but not sexual) abuse on the one hand and dimensions of emotion dysregulation on the other. Further analyses indicated that difficulties controlling impulsive behaviors when distressed accounted for the associations of both childhood physical and emotional abuse with probable PTSD status. Findings of the present study highlight a potential mechanism underlying the relationships between both childhood emotional and physical abuse and PTSD in SUD patients.