Main findings indicate that California’s drug possession prison population has decreased since Proposition 36 passed and that the overall prison population has grown at a much slower rate than was projected since 2000. California’s incarceration rate fell 4 percent during the same period that the United States incarceration rate rose slightly. In comparison to the 10 largest State prison systems, since 2000 California experienced the largest decline in drug prisoners. California’s violent crime rate has also declined since 2000 at a rate higher than the national average. Data concerning drug courts suggest that Proposition 36 drug treatment completion rates are comparable to the national average and that the positive impact of diverting drug offenders to treatment is greater than the effectiveness of using incarceration to prevent drug use. Finally, the evidence indicates that Proposition 36 has saved the State of California hundreds of millions of dollars since its passage through reduced jail and prison admissions, from closing the Northern California Women’s facility, and through savings accrued by avoiding prison construction costs. Despite these overwhelmingly positive findings about correctional reform efforts in California, there is evidence that California may be backsliding into the “get tough” era of the 1990s that resulted in soaring prison populations. Currently trends suggest that drug possession prison admissions are on the rise, perhaps due to increased law enforcement efforts and because drug offenders are being sentenced to prison for violating the terms of their Proposition 36 drug treatment provisions. It is recommended that budgets for drug treatment be increased and that offenders are matched with the appropriate treatments to improve chances of success. Tables, figures, endnotes, footnotes