Project Summary The COVID-19 public health emergency gave an extraordinary exogenous shock to SUD treatment organizations, forcing rapid changes in how they provide care. Before COVID-19, the treatment model relied heavily on brick-and-mortar clinics to provide in-person medical care and psychosocial treatment, including specialty outpatient addictions treatment (SOAT) and pharmacotherapy provided through medical office-based addictions treatment (OBAT). Due to government mandates for physical distancing and relaxation of restrictions for using telehealth, both SOAT and OBAT providers quickly and fundamentally changed their workflows, including: new forms of medical screening and medication management; greater flexibility in allowing patient self-dosing of medication at home; treatment through individualized and group meetings via telehealth; reduced reliance on drug use screening; and new strategies for treatment engagement. These changes will have unknown effects on treatment retention, use of pharmacotherapy for addictions, and longer- term outcomes. The outpatient treatment system responses—both temporary and enduring—to these external shocks will take many forms depending on the organizational and environmental context in which programs operate. There is concern that Black/African American and Latinx patients—who are more likely to receive care in more poorly resourced programs and have lower access to eHealth technology—will receive poorer quality care and worse outcomes. We will employ a social-ecological framework to examine the conditions under which outpatient treatment across New York State adapted to the exogenous shock and analyze relationships between new clinical practices (e.g., use of telehealth) and proximal (e.g., retention, use of pharmacotherapy) and distal (e.g., overdoses, emergency department visits) markers of patient outcomes. Further, we will examine racial/ethnic variation that may indicate disparities in care as well as organizational and community factors that may account for disparities. We propose an explanatory sequential mixed-methods design to study both short term and longer-term changes to treatment services and outcomes. We will first use administrative data—joining a state registry of SUD treatment episodes with Medicaid—to study variation in treatment practices across 545 SOAT clinics and 3100 OBAT providers. We will examine changes to treatment practice: clinical delivery (e.g., use of telehealth, mix of group versus individual counseling), use of pharmacotherapy (e.g., remote induction, greater flexibility in methadone self-administration), and retention. We will then examine the association between these practice changes and treatment outcomes, such as overdoses, substance-related emergency department visits, and hospitalizations. We will employ qualitative methods to develop an understanding of the quantitative findings by examining organizational characteristics of programs representative of those that...