Throughout history, technological progress has transformed population health, but the distributional effects of these gains are unclear. New substitutes for older, more expensive health technologies can produce convergence in population health outcomes, but may also be prone to “elite capture” leading to divergence. This paper studies the case of penicillin using detailed mortality statistics and exploiting its sharply-timed introduction in Italy after World War II. We find penicillin reduced both the mean and standard deviation of infectious diseases mortality, leading to substantial convergence across disparate regions of Italy. Our results do not appear to be confounded by competing risks or mortality patterns associated with World War II.