Bradley, Valerie DianeBackground. Successful outcomes in substance use disorder treatment are often narrowly defined as retention in care, substance use cessation, and the prevention of recurrent substance use. These widely utilized benchmarks may overlook key patient-centered indicators of success. Few studies have sought patient perspectives to establish a representative definition of successful treatment outcomes for opioid use disorder (OUD), with historically marginalized individuals facing the least representation and the largest inequities in care. With overdose-related deaths increasing to over 112,000 in the 12 months preceding May 2023 and a disproportionate impact on racially minoritized populations, understanding comprehensive patient-centered definitions of successful treatment in minoritized populations is an imperative endeavor for research, treatment planning, and policy. This study aimed to understand how patients and providers at an outpatient methadone treatment program in Baltimore City describe patient-centered successful treatment outcomes.Methods. We conducted qualitative interviews and focus groups with 32 patients, staff, and peer recovery specialists (PRSs) at a Baltimore-based outpatient methadone treatment program predominantly serving low-income, racially minoritized individuals with OUD. Semi-structured interview guides prompted patients (n=20) to describe success in methadone treatment and staff and PRSs (n=12) to describe their observations of patients' success in treatment. Qualitative data were transcribed, coded, and analyzed using thematic analysis. We utilized the Health Equity Implementation Framework to contextualize findings across multiple domains and explore potential influences on equitable outcomes of treatment success. Results. Five key themes emerged to demonstrate how patients and their providers define patient-centered successful methadone treatment outcomes, including (1) improvements in general health, (2) productivity and accomplishment, (3) social improvements, (4) substance use changes, and (5) treatment engagement. Patients and providers were generally in agreement on these five overarching themes. Conclusion: Findings suggest patient-centered definitions of success in methadone treatment span psychosocial, environmental, behavioral, health-related, and other factors beyond the traditionally measured outcomes of treatment retention and substance use abstinence. Working toward a more representative definition of methadone treatment success—integrating patient perspectives, particularly minoritized individuals who often face the greatest obstacles in care—may have significant clinical, research, and policy implications for improving the patient experience and outcomes in methadone treatment.enThesisClinical psychologyMedication for opioid use disorderOpioid use disorderPatient-centeredSubstance useTreatment outcomesTreatment success