BackgroundTreatment for methamphetamine and other stimulants can be effective but dropout and relapse are very high. Abstinence is the conventional outcome used to evaluate treatment success, but sefining treatment success in this way misses opportunities to promote improved health even when abstinence is not achieved. Reducing methamphetamine and stimulant use without abstinence is associated with many positive outcomes. However, little is known about drug use patterns during treatment or trends in use over time. MethodsWe used the Treatment Episode Dataset-Discharges (TEDS-D) to identify treatment episodes that had a stimulant drug indicated as the primary substance of use (2017-2021; N=251,841; methamphetamine, cocaine, other amphetamines, or other stimulants). Our outcome was the change in the frequency of drug use between admission and discharge (decreased use with abstinence, decreased use without abstinence, increased use). We used multiple logistic regression to model a change in drug use frequency, predicted by year, stimulant type, and their interaction. ResultsNearly two-thirds of the sample (60%) had methamphetamine indicated as the primary stimulant of use. There was a decrease in the predicted rate of abstinence over time and worsening trends were strongest among those using methamphetamine. Daily and periodic drug use at both admission and discharge (no change in use) became worse over time, particularly for those using methamphetamine. ConclusionTreatment outcomes worsened over time and declined fastest among those reporting methamphetamine. Abstinence was rare and most treatment clients did not change their drug use behavior. We recommend a renewed focus on evidence-based harm reduction while the nation’s treatment systems continue grappling with the stimulant crises.