Purpose of Review <p>Alcohol and cannabis are substances commonly used by people with or made vulnerable to HIV. With changing cannabis legalization, cannabis use has been on the rise, including simultaneous use (co-use) with alcohol. Prior reviews have assessed patterns, correlates, and consequences of alcohol and cannabis co-use. We conducted a scoping review to examine alcohol and cannabis co-use and HIV risk, treatment, and prevention outcomes.</p> Recent Findings <p>We identified 818 unique articles across seven databases through December 2024, of which, 28 met criteria. There was substantial heterogeneity in the conceptualization of co-use, measurement, and analysis methods. Many studies employed cluster analyses, with alcohol and cannabis co-use often included in the context of polysubstance use. Only one study utilized event-level methods to assess simultaneous use and sex behaviors. Findings on the relationship between alcohol and cannabis co-use and antiretroviral medications (ARV) outcomes and sex behaviors are mixed, though several studies suggest that co-use may be associated with poorer ARV adherence and increased engagement in sex behaviors that increased HIV risks.</p> Summary <p>This review highlights substantial heterogeneity in how alcohol and cannabis co-use is conceptualized and measured. Few studies examined simultaneous use specifically or disentangle co-use from broader polysubstance patterns. Research prioritizes standardized and event-level assessment can enhance accuracy of measurement and elucidate contextual factors for alcohol and cannabis co-use. Understanding how alcohol and cannabis co-use affects populations disproportionately impacted by HIV can inform more effective and tailored HIV treatment and prevention strategies. </p>