Antiretroviral therapy is complicated and can be hard to follow. For HIV-infected patients, adhering to a prescribed regimen of antiretroviral therapy provides important individual survival benefits, and also reduces the risk of developing drug resistant viral strains that can infect others. Even patients with initially high levels of adherence to antiretroviral therapy face the challenge of maintaining those levels over time. Ideally, clinicians caring for HIV-infected patients would have some way of predicting which patients are most likely to need help in adhering to a prescribed regimen and an early warning system alerting them to their patients’ non-adherence. This Issue Brief summarizes recent studies whose findings may help clinicians predict and monitor their patients’ adherence before treatment failure occurs.