This study assessed the effectiveness of a discharge planning program implemented in three Oklahoma state prisons to assist inmates with serious mental illness to enroll in Medicaid on the day of release or soon thereafter. The program had significant positive effects. On the day of release, 25 percent of inmates who received program services were enrolled in Medicaid, compared with 8 percent of inmates at the same facilities in the two years before the new program was implemented and 3 percent for inmates in comparison facilities. The effect was even greater three months after release.