Prisons are saturated with trauma survivors; yet trauma has not been the focal point of corrections-based treatment. This is the first randomized controlled trial assessing the effectiveness of a Peer-facilitated trauma-specific intervention among men incarcerated for violent offenses (Exploring Trauma: A 6-Session Brief Intervention for Men). The sample consisted of 221 participants (131 treatment / 90 waitlisted control group). Independent t tests determined change over 6-8 weeks on anxiety, depression, mental health, current traumatic distress, and anger. Hypotheses were predominantly supported. Significant improvement was found for the intervention group compared with the waitlisted control group on 11 of the 13 trauma-related outcomes. The greatest effect sizes ranged from .46 for mental health functioning, .42 for trait anger composite, and .40 for anxiety. Support for the effectiveness of this brief intervention and capability of a Peer-facilitated model of delivery was demonstrated. Future research should replicate the methodology and incorporate records data and post-release outcomes.