In the battle to control HIV, mass antiretroviral treatment (ART) costs $500 to $900 per person per year. Bor et al. (p. [Related article:] 961 ) calculated the impact of intensifying ART on the life expectancy of people living in rural KwaZulu Natal. The dates of death were collected from a population of about 100,000 people during 2000–2011: Four years before and 8 years after the scaling up of ART. Life expectancy of adults increased by more than 11 years after ART was expanded, and the economic value of the lifetimes gained were calculated to far exceed the cost of treatment. Tanser et al. (p. [Related article:] 966 ) followed nearly 17,000 HIV-uninfected individuals in KwaZulu-Natal over an 8-year period. Holding other HIV risk factors constant, individual HIV acquisition risk declined significantly with increasing ART coverage of HIV-infected people. Adult life expectancy has increased by 11 years in rural KwaZulu-Natal since the 2004 public-sector scale-up of HIV treatment. The scale-up of antiretroviral therapy (ART) is expected to raise adult life expectancy in populations with high HIV prevalence. Using data from a population cohort of over 101,000 individuals in rural KwaZulu-Natal, South Africa, we measured changes in adult life expectancy for 2000–2011. In 2003, the year before ART became available in the public-sector health system, adult life expectancy was 49.2 years; by 2011, adult life expectancy had increased to 60.5 years—an 11.3-year gain. Based on standard monetary valuation of life, the survival benefits of ART far outweigh the costs of providing treatment in this community. These gains in adult life expectancy signify the social value of ART and have implications for the investment decisions of individuals, governments, and donors.