Researchers partnered with Innovations for Poverty Action and Bangladeshi policymakers to test various strategies to increase mask-wearing and assess the impact of community mask wearing on SARS-CoV-2 infection rates. They found that a four-part intervention tripled mask usage and increased physical distancing. Further, this increase in mask-wearing reduced symptomatic SARS-CoV-2 infections. When surgical masks were employed, 1 in 3 symptomatic infections were avoided for individuals 60+ years old—the age group that faces the highest risk of death following infection. This was the first large-scale randomized evaluation to demonstrate the effectiveness of masks in a real-world setting.