PROJECT SUMMARY/ABSTRACT Alcohol use disorder (AUD) is an alarming public health problem that costs the US more than $249 billion annually. AUDs leads to a devastatingly diverse set of negative health outcomes, including significantly increased risk of hypertension, stroke, pancreatitis, liver cirrhosis, Alzheimer’s disease, multiple cancers, and multiple types of cognitive dysfunction. Disulfiram, naltrexone, and acamprosate are the only FDA-approved medications for the treatment of AUD and are only modestly effective. Zonisamide (ZON) is an anticonvulsant medication with GABAnergic, glutamatergic and monoaminergic effects which has shown significant promise in animal and human laboratory settings, and small clinical trials for the treatment of AUD. ZON could represent a critical new tool for clinicians, but previous studies have been limited by a couple of key factors (e.g., no objective evidence recent alcohol consumption, no objective evidence of medication adherence) that this study is designed to overcome. Theoretically framed within the Addiction Neuroclinical Assessment with hypothesized mechanisms in core domains (i.e., incentive salience, negative emotionality and cognitive function), and proceeding from a sound scientific premise we will target reduced alcohol use among AUD patients in primary care using a carefully designed combination of contingency management (CM, or incentives in exchange for objectively verified evidence of behavior) delivered at thrice-weekly visits during the first 4- weeks of ZON treatment to jumpstart reductions in drinking. For the remaining 8-weeks of ZON, CM will be delivered at weekly visits in exchange for evidence of 100% or higher medication adherence. The goal of this study is to complete a double-blind, placebo-controlled RCT to evaluate the ability of ZON to significantly decrease alcohol use among treatment-seeking AUD adults. Individuals will be randomized into 1 of 2 trial arms that will receive: 1) ZON plus standard treatment (ST), which includes Take Control bibliotherapy modules and CM through the 12-week treatment period (ZON+ST), or 2) Matched placebo plus ST (PLO+ST). The primary outcome will be biochemically-verified alcohol use during the treatment period. We will use a 2-week, single- blind placebo induction period wherein participants will be required to demonstrate a 75% medication adherence rate before continuing into the 12-week treatment period. Follow-up will occur at 1, 6 and 12-months. Our Specific Aims are to: 1) Determine if ZON+ST is more effective than PLO+ST for reducing biochemically- verified alcohol use and other alcohol use outcomes; 2) Identify ANA-based mediators of treatment response across the treatment groups; 3) Determine a.) if biological sex, baseline depression and baseline severity of alcohol use interacts with treatment assignment to produce differential changes in our primary and secondary outcomes; and b.) whether groups differ on adverse events or medication...