A model of private and public behavior to mitigate disease transmission during the COVID-19 pandemic over the past year in the United States addresses two questions: What dynamics of infections and deaths should we expect to see from a pandemic? What are our options for mitigating the impact of a pandemic on public health? I find that behavior turns what would be a short and extremely sharp epidemic into a long, drawn-out one, with, at best, a modest impact on the long-run death toll from the disease. Absent the development of a technological solution, such as vaccines or life-saving therapeutics, additional public health interventions suffer from rapidly diminishing returns in improving long-run outcomes. In contrast, rapidly implemented nonpharmaceutical interventions, in combination with the rapid development of technological solutions, could have saved nearly 300,000 lives relative to what is now projected as of mid-June 2021 to occur over the long run.