Objective: Because physical exercise improves psychological functioning, it may be beneficial to college students with maltreatment histories. Thus, we tested the hypotheses that cumulative maltreatment would negatively affect psychological functioning, physical exercise would positively affect psychological functioning, and emotion regulation difficulties would negatively contribute to the prediction of psychological functioning. Participants: Participants were 90 undergraduate students (71.1% female, 65.6% white). Methods: Participants completed questionnaires regarding their maltreatment and physical exercise history, emotion regulation difficulties, and psychological functioning. Results: Cumulative maltreatment was negatively correlated with self-esteem and positively correlated with PTSD/depression and frequent exercise was negatively correlated with PTSD/depression. Emotion regulation difficulties impacted the relationships between maltreatment history and psychological functioning, and accounted for much of the variability in psychological functioning. Cumulative maltreatment and exercise impacted different domains of emotion regulation which in turn uniquely affect psychological functioning. Conclusions: Therapeutic interventions should aim to improve these specific emotion regulation abilities.