ENGLISH :
To examine why court mandated offenders dropout of drug treatment and to compare their characteristics, treatment experiences, perceptions, and outcomes with treatment completers, we analyzed self-reported and administrative data on 542 dropouts (59%) and 384 completers (41%) assessed for Proposition 36 treatment by thirty sites in five California counties during 2004. At intake, dropouts had lengthier criminal histories, lower treatment motivation, more severe employment and psychiatric problems, and more were using drugs, especially heroin. Relatively fewer dropouts received residential treatment and their retention was much shorter. A similar proportion of dropouts received services as completers and the mean number of services received per day by dropouts was generally more, especially to address psychiatric problems, during the first three months of treatment. The most commonly offender-reported reasons for dropout included low treatment motivation (46.2%) and the difficulty of the Proposition 36 program (20.0%). Consequences for dropout included incarceration (25.3%) and permission to try treatment again (24.0%). Several factors predicting drug treatment dropout were identified. Both groups demonstrated improved functioning at one-year follow-up, but fewer dropouts had a successful outcome (34.5% vs. 59.1%) and their recidivism rate was significantly higher (62.9% vs. 28.9%) even after controlling for baseline differences. Understanding factors associated with drug treatment dropout can aid efforts to improve completion rates, outcomes, and overall effectiveness of California's Proposition 36 program. Findings may also aid a broader audience of researchers and policy analysts who are charged with designing and evaluating criminal-justice diversion programs for treating drug-addicted offenders. (Author' s abstract)