Potent antiretroviral therapy (ART) has transformed HIV from a death sentence to a chronic illness. Accordingly, the goal of HIV care has shifted from delaying death to achieving optimal health outcomes through ART treatment. ART treatment success hinges on medication adherence. Extensive research has demonstrated that the primary barriers to ART adherence include mental illness, especially depression and substance abuse, as well as histories of traumatic experiences such as childhood sexual and physical abuse. These psychosocial factors are highly prevalent in people living with HIV/AIDS (PLWHA) and predict poor ART adherence, increased sexual risk behaviours, ART treatment failure, HIV disease progression and higher mortality rates. The efficacy of standard mental health interventions, such as antidepressant treatment and psychotherapy, has been well-defined, and a small but growing body of research demonstrates the potential for such interventions to improve ART adherence and reduce sexual risk behaviours. Despite this evidence, mental disorders in PLWHA frequently go undiagnosed and untreated. Challenges to the provision of mental healthcare for PLWHA in HIV clinical settings include time and resource constraints, lack of expertise in psychiatric diagnosis and treatment, and lack of available mental health referral services. Future research should prioritize the evaluation of mental health interventions that are cost-effective and feasible for widespread integration into HIV clinical care; the impact of such interventions on ART adherence and clinical outcomes; and interventions to identify individuals with histories of traumatic experiences and to elucidate the mechanisms through which such histories pose barriers to effective HIV treatment.