This book reviews and advances the theoretical and empirical knowledge at the intersection of opinion change and democracy. Specifically, the volume addresses how opinion change and political persuasion unfold in three main domains of media effects: private media (i.e., news organizations), public service media (state-own media services), and social media platforms. Divided in these three different sections, the volume serves as a venue to discuss and further advance the most recent theoretical assumptions and empirical findings that underpin our current understanding on how media influence public opinion and shape liberal democracies. The book also explores how media literacy and critical thinking can mitigate the effects of misinformation and propaganda, emphasizing the importance of educating the public to discern credible information from deceptive content. Furthermore, it discusses the ethical implications of media practices and the responsibilities of media producers in maintaining the integrity of democratic discourse. By highlighting these aspects, the book provides a comprehensive understanding of the complex interplay between media, public opinion, and democracy, offering valuable insights for scholars, policymakers, and anyone interested in the role of media in shaping public opinion.