Much time has been spent over the past decade debating whether social media contribute to democracy. Drawing on an original study of internet users across nine Western democracies, Outside the Bubble offers an unprecedented look at the effects of social media on democratic participation. This book argues that social media do indeed increase political participation in both online and face-to-face activities–and that they expand political equality across Western democracies. In fact, Cristian Vaccari and Augusto Valeriani find that, for the most part, social media do not constituteecho chambers or filter bubbles as most users see a mixture of political content they agree and disagree with. Various political experiences on social media have positive implications for participation and active political involvement: social media allow citizens to encounter clearly identifiablepolitical viewpoints, facilitate accidental exposure to political news, and enable political actors and ordinary citizens to reach voters with electoral messages designed to mobilize them. Moreover, political interactions occurring on social media do not only benefit citizens who are alreadyinvolved, but boost participation across the board. This is because social media offer both additional participatory incentives to the already engaged and new political opportunities for the less engaged. By adopting a comparative approach, Vaccari and Valeriani also show that political institutions matter since some political experiences on social media are more strongly associated with participation in majoritarian systems and in party-centric systems. While social media may contribute to manysocietal problems, they can help address at least two important democratic ills: citizens’ apathy towards politics, and inequalities between those who choose to exercise their voice and those who remain silent.