This study discusses the pretest and posttest results of a batterer's intervention program (BIP) implemented within a California state prison substance abuse program (SAP), with a recommendation for further programs to be implemented within correctional institutions. The efficacy of utilizing correctional facilities to reach offenders who self-report domestic violence behaviors is evaluated. The 52-week curriculum was designed to address the unique environment of a correctional setting and the characteristics of the participants, using established psycho-educational and cognitive-behavioral methods. A repeated measurement design was used to evaluate the participants' cognitive changes, including acceptance of personal responsibility for abusive behaviors. Using a modified Abusive Behavior Inventory along with Criminal Thinking Scales, participants were tested at intake and again at 18 sessions. Their responses were statistically significant to p less than 0.01. (Contains 1 table.)