Antiretroviral therapy has improved the quality and length of life of millions of individuals affected by human immunodeficiency virus type 1 (HIV-1). The capacity of these drugs to indefinitely suppress HIV-which has a well-known capacity for escaping antiviral pressures-is surprising. In this issue of Science Translational Medicine, Shen et al. use a combination of mathematical modeling and experiment to examine the potency of anti-HIV drugs. They show that non-nucleoside reverse transcriptase inhibitors and protease inhibitors exhibit cooperative dose-response curves-a finding that has implications for the treatment of HIV as well as other viral infections, such as hepatitis C.