Half of adults with HIV experience HIV-Associated Neurocognitive Disorder (HAND). HIV infects microglial and macrophages in the brain, resulting in a neurotoxic environment that inhibits the function of neurons, thus impairing cognition. Social workers require an understanding of how HIV-related cognitive dysfunction develops within the larger context of mental illness, substance use, and socioeconomic status. This article briefly reviews the clinical diagnosis of HAND and some interrelated neurobiological and psychosocial factors. Research implications for improving cognition are important as one considers: (1) The impact of the aging process on cognition and (2) the growing number of older adults with HIV.