Multiple studies have demonstrated decreased recidivism and increased treatment engagement for individuals with serious mental illness involved in Mental Health Courts (MHC); however, the limited availability of social and fiscal resources requires an analysis of the relationship between a program's effectiveness and its costs. In the current study, transactional costs analysis (TCA) was used to calculate outcomes associated with treatment, arrest, and confinement in the 12-month post-MHC. Total outcome costs for the Successful Group ($16,964) significantly differed from the Unsuccessful ($32,258) and Compare Groups ($39,870). Costs associated with the higher number of arrests for those in the Compare Group created the largest differences. Total cost savings between Successful and Compare (M = $22,906) equated to $916,240 and savings between Unsuccessful and Compare (M = $7612) were $494,708. The total combined cost savings for participants in the 12-month post-MHC period was $1,411,020. Although it is important to understand that MHCs and the individuals they serve vary and these results are for a felony-level court, policymakers and researchers can use these results to guide their decisionmaking. (Publisher abstract modified)