Abstract: A country’s relational mobility (i.e., the community-level tendency to engage with strangers and freely choose friends) appears to influence the initial spread rate of COVID-19. Salvador and colleagues analyzed the growth curves of confirmed cases and deaths due to COVID-19 in 39 countries. They found that growth was accelerated in countries with higher relational mobility scores, measured in a previous study by the extent to which people perceive others in their communities as socially open and seeking new friendships. These findings underscore the need for social distancing to “flatten the curve,” especially in countries that value social openness.