Many people at risk for or already infected with HIV abuse alcohol, contributing to the difficulties in preventing the spread of the infection and treating infected patients. Thus, alcohol-abusing patients may delay testing for HIV, accessing appropriate medical care, and initiating antiretroviral therapy (ART), which may hasten disease progression to full-blown AIDS. Alcohol abuse also increases the risk of HIV infection by promoting risky behaviors and counteracting efforts to minimize the risk of infection, prevent transmission of the virus to others once exposure has occurred, and reduce the risk of progression and organ or tissue injury after infection. In HIV-infected people undergoing treatment, concurrent alcohol abuse often renders treatment ineffective because patients frequently fail to adhere to the strict treatment regimens necessary to achieve control of the infection. Moreover, alcohol may interact with ART medications and exacerbate adverse effects of these medications. Future research needs to better integrate behavioral and biological research to identify strategies to prevent the spread of HIV infection in alcohol-abusing populations as well as focus on translational research to effectively implement promising approaches on a large scale.