Using Facebook's release in a given language as an exogenous source of variation in access to social media where the language is spoken, we show that Facebook has had a significant and sizable positive impact on citizen protests. By exploiting variation in a large sample of countries during close to 15 years and combining both aggregate and individual-level data, we confirm the external validity of previous research documenting this effect for specific contexts along a number of dimensions: geographically, by regime type, temporally, and by the socioeconomic characteristics of both countries and social media users. We find that "coordination" effects that rest on the "social" nature of social media play an important role beyond one-way information transmis- sion, including a "liberation effect" produced by having a direct outlet to voice opinions and share them with others. Finally, we explore the broader political consequences of increased Facebook access, helping assess the welfare consequences of the increase in protests. On the negative side, we find no effects on regime change, democratization or governance. To explain this result, we show there are no effects on other political engagements, especially during critical periods, and that social media access also helps mobilize citizens against opposition groups, especially in less democratic areas. On the positive side, we find that Facebook access decreases internal conflict, with evidence that this reflects increased visibility deterring violence and that social media and the resulting protests help voice discontents that might otherwise turn more violent.