Abstract The growth of social media—and, in particular, Twitter and Facebook—has led scholars to study its effects on mass behavior and protest. But leaders are also active on social media. They use their accounts to communicate with domestic and international audiences. By the end of 2014, more than 76 percent of world leaders had an active presence on social media. What explains variation in their adoption and use of social media? We look at several different potential hypotheses: higher income per capita and internet penetration (modernization), social pressure, level of democratization, and geographic spread of adoption (diffusion). We find strong support that (1) increased political pressure from social unrest and (2) higher levels of democratization correlate with leader adoption of social media platforms. Although our findings are correlational, they reveal that institutional and political pressures are related to social media adoption and the political communication of world leaders.