 Antiretroviral agents are presently administered to adults in standard fixed doses. However, the same dose does not produce the same systemic and intracellular concentrations in all patients. Recent research has shown that adjusting the doses of antiretroviral agents to achieve target concentrations in plasma is associated with an improved anti-HIV response compared with standard dose therapy. This study will extend the paradigm of concentration-controlled therapy to develop intensified pharmacologic regimens for patients experiencing persistent viremia while receiving antiretroviral therapy. 