This book presents a comprehensive examination of public opinion in the democratic world. Built around chapters that highlight key explanatory frameworks used in understanding public opinion, the book presents a coherent study of the subject in a comparative perspective, emphasizing and interrogating immigration as a key issue of high concern to most mass publics in the democratic world. Key features of the book include: Covers several theoretical issues and determinants of opinion such as the effects of personality, age and life cycle, ideology, social class, partisanship, gender, religion, ethnicity, language, and media, highlighting over time the effects of political, social, and economic contexts. Each chapter explores the theoretical rationale, mechanisms of effect, and use in the scholarly literature on public opinion before applying these to the issue of immigration comparatively and in specific places or regions. Widely comparative using a nine-country sample (Australia, Canada, France, Germany, Italy, Portugal, Switzerland, the United Kingdom, and the United States of America) in the analysis of individual-level determinants of public opinion about immigration and extending to other countries like Belgium, Brazil, and Japan when evaluating contextual factors. This edited volume will be essential reading for students, scholars, and practitioners interested in public opinion, political behaviour, voting behaviour, politics of the media, immigration, political communication, and, more generally, democracy and comparative politics.