Previous research has suggested that time spent in treatment is the most important predictor of therapeutic community treatment outcomes. Although level divisions or treatment stages represent the basic structure for segmenting responsibility and authority within traditional therapeutic communities, the relationship of this treatment component to treatment outcome has not previously been investigated. OBJECTIVE To test the hypothesis that higher treatment level attainment, more time spent in treatment and additional time spent within a treatment level has a linear association with improvements at outcome. METHODS Retrospective quasi-experimental. METHODS Four hundred and twenty-seven ex-residents, stratified according to their highest level of treatment in the Melbourne Odyssey House therapeutic community between 1984 and 1988 were targeted for follow-up and 60% were successfully located and interviewed an average of 5.6 years after their first Odyssey entry. Analysis of official records of methadone treatment, convictions and incarcerations demonstrated no post-treatment differences comparing those interviewed with those not interviewed. METHODS Drug use, criminal involvement and employment. FINDINGS. Although both level attainment and time spent in treatment had a linear relationship to improved outcomes, level attainment was a better predictor of outcomes at treatment exit. An unexpected finding was that those who had spent the median time or longer in particular levels demonstrated worse outcomes on official conviction records and on self-reports of employment compared to those remaining for less than the median time. CONCLUSIONS The results suggest that it may be level progress rather than simply time spent in treatment that best explains improved functioning following exit from the therapeutic community.