This report provides an assessment of the effectiveness of Kansas Senate Bill 123 (SB 123), enacted in 2003 by the Kansas State Senate, which "created mandatory community-based supervision and drug treatment for nonviolent offenders convicted of a first or second offense of simple drug possession." The assessment examined the bill's combined impact on diversion, recidivism rates, and overall prison population rates, as well as its impact on the work routines of the State's criminal justice system professionals and the bill's implementation process. The assessment examined the effectiveness of SB 123 over its first 5 years of implementation and found that while offenders sentenced to SB 123 had lower incarceration and revocation filings at 12 months than those sentenced to standard supervision, by 24 months, the differences in recidivism measures had disappeared. It was also found that SB 123 increased the long-term odds of incarceration and revocation filings compared to court services. At the system level, SB 123 resulted in a slight reduction in drug possessors entering prison thus alleviating prison populations and reducing prison costs. These findings indicate that SB 123 has more of an impact at the system-level as compared to the individual-level. Successes noted from the implementation of SB 123 were the increased availability of better treatment programs for drug offenders, improved supervision and referral practices, improved revocation practices, and more open communication among criminal justice stakeholders at the State and local levels. Recommendations for improving SB 123 are discussed. Figures, tables, appendixes, and references