Virus-specific CD4⁺ T helper lymphocytes are critical to the maintenance of effective immunity in a number of chronic viral infections, but are characteristically undetectable in chronic human immunodeficiency virus–type 1 (HIV-1) infection. In individuals who control viremia in the absence of antiviral therapy, polyclonal, persistent, and vigorous HIV-1–specific CD4⁺ T cell proliferative responses were present, resulting in the elaboration of interferon-γ and antiviral β chemokines. In persons with chronic infection, HIV-1–specific proliferative responses to p24 were inversely related to viral load. Strong HIV-1–specific proliferative responses were also detected following treatment of acutely infected persons with potent antiviral therapy. The HIV-1–specific helper cells are likely to be important in immunotherapeutic interventions and vaccine development.