BACKGROUND: Opioid tapering is recommended when risks of chronic opioid use outweigh benefits. Little is known about patient characteristics or factors related to tapering success. OBJECTIVE: To identify characteristics that predict a 50% reduction in opioid use and qualitatively characterize factors that impact tapering success. METHODS: We used multilevel hierarchical modeling to identify predictors of a 50% reduction in opioid use among Kaiser Permanente Northwest patients who underwent pharmacist-led tapering between 2012 and 2017. We conducted qualitative interviews among patients and pharmacists to identify factors impacting tapering success. RESULTS: We identified 1,384 patients who, on average, were dispensed 207 milligram morphine equivalents per day (MMED) at baseline. After 12 months, 56% of patients reduced their opioid use by 50%. Increased odds of 50% reduction were associated with younger age 21–49 years (OR: 1.32, p=0.004), prior surgery (OR: 2.24, p