Adherence has proven to be Achilles' heel of antiretroviral therapy. To achieve the nearly perfect adherence apparently necessary for optimal effects, individuals often require assistance. In this review, we examine antiretroviral therapy adherence intervention studies and reviews published through January 2003 as well as abstracts of ongoing National Institutes of Health-funded research projects aimed at enhancing antiretroviral therapy adherence. The 21 published studies we located utilized 4 intervention strategies: cognitive-behavioral, behavioral, directly observed therapy, and affective. Most of these were pilot or feasibility studies. However, the 4 randomized controlled trials conducted with adequate methologic rigor suggest some promising yet preliminary effects of a pharmacist-led individualized intervention, a cognitive-behavioral educational intervention based on self-efficacy theory, and cue-dose training when combined with monetary reinforcement. The 39 ongoing federally funded studies offer superior methodologic sophistication and include some innovative strategies, such as the use of handheld devices, two-way pagers, and alarmed medication vials, along with enhancement of social and emotional support.