This book examines the causes of a growing wave of digital activism across developing countries, arguing that it is driven by social change, rather than technological advancement alone. Beginning with an investigation into the modernization of ‘middle-income countries’ and its ramifications for political culture, the book examines large-scale social media protest during political controversies in Indonesia.The book connects empirical evidence to classic theories of value change and political behaviour. It departs from a narrow ‘digital divide’ framing whereby Internet access produces Internet activism. It introduces the concepts of ‘digital self-expression’ and of ‘middle-class struggles’ to capture the value-stratified nature of political engagement in the online sphere. Drawing on a blend of ‘big-data’ text analyses, representative opinion research, and socioeconomic household analyses, a rich picture of the determinants of digital activism emerges.This truly cross-disciplinary book will appeal particularly to students and scholars in Political Science, Sociology, International Development, and Communication, but also to anyone eager to learn about political activism, social transformation, and new media from a global perspective.