"Proposition 36 introduced an unprecedented number of clients into California’s drug treatment system. Overall treatment admissions increased by 11% to 34% during the first year in 4 of the 5 counties studied, with an 11% increase statewide. No parallel increases have been observed in drug use prevalence14 or in drug law enforcement15 during these periods. In the law’s second year, few changes in overall admissions were observed in the 5 counties and the state, but the number of Proposition 36 offenders entering drug treatment continued to increase in all counties and statewide (50% increase over Year 1). Except for San Francisco county, Proposition 36 clients in Year 2 constituted 18% to 42% of the total admissions in the studied counties’ treatment systems and 20% of the state’s treatment system, which is a significant proportion given the brief time since implementation. This expansion has occurred mainly in ODF [Outpatient Drug Free] programs, with concurrent reductions in self-referrals and admissions to methadone programs. These findings suggest that treatment capacity and availability for non–Proposition 36 clients might be compromised in the majority of California counties."