Drug treatment court (DTC) is a diversion program for individuals with drug-related crimes. However, the DTC literature is conflicting with regard to substance use and recidivism outcomes. This study examines factors associated with improved client outcome trajectories among a multisite, national DTC sample. We conducted a secondary analysis of 2,295 participants using the Global Appraisal of Individual Needs assessment tool. Participants in community-based treatment comprised a nonequivalent comparison group. Zero-inflated Poisson (ZIP) regression examined client sociodemographics in relation to substance use and rearrest at 6-month follow-up. Employed DTC clients were more likely to abstain from substances, but among all study participants, higher baseline use, male gender, and employment predicted substance use. Similarly, among DTC clients, older age and employment predicted no rearrests, but among all study participants, older and employed individuals had worse arrest outcome trajectories. Future work is needed to better understand how client characteristics may inform individualized treatment approaches.