In this project, investigators aim to test the hypothesis that CBD will reduce alcohol drinking in individuals with AUD comorbid with PTSD. CBD is currently a medical research focus because it shows promise for treating anxiety and other brain disorders, but does not produce a 'high' like other parts of cannabis, has not been shown to be addictive, and is safe, with few or no side effects. AUD, which is one of the most common and most debilitating psychiatric conditions, is often associated with other comorbid psychiatric disorders - in particular, PTSD: depending on the population studied, 30-60% of individuals with AUD also have PTSD, with high comorbidity rates in military veterans. Evidence from animal models and clinical studies suggests that the negative emotion caused by PTSD symptoms intensifies craving for alcohol during alcohol withdrawal, perpetuating the addictive cycle; further, evidence shows that the brain circuits underlying negative emotion and addiction are linked in a forebrain area called the extended amygdala, which provides a neuropharmacological target to simultaneously treat both negative emotion and alcohol addiction in individuals with AUD and PTSD. CBD is known to inhibit brain activity in the extended amygdala, leading to reduced anxiety in both animal models and humans. CBD also reduces addictive alcohol seeking in animal models.