The document summarizes the history and impact of prison-based therapeutic communities (TCs) in California over the past 20 years. It notes that TCs significantly reduced recidivism and improved institutional management compared to normal prison settings. However, rapid growth diluted the model and loss of funding and support has threatened the initiative. While not perfect, the TCs remain one of the largest treatment initiatives in corrections and have significantly lower recidivism rates than alternatives, showing the potential benefits of rehabilitation over punitive approaches.