Crystallizing Public Opinion by Edward L. Bernays was the first book-length definition of public relations, explaining how it is more than press agentry or publicity. It helped crown Bernays as the "father of public relations," and has never been out of print in 100 years. But a lot of other things have changed. Newspapers are no longer people's primary source of news, the creation of content has been democratized, and the very nature of public opinion itself has changed as our understanding of "publics" has evolved. The longtime guidebook to public relations now needs its own native guide. That's where this 100th anniversary edition comes in. This edition is more than a reprint. It provides virtually line by line annotations explaining who Bernays was writing about or quoting, sometimes correcting factual errors, and consistently providing context to make Bernays's advice and observations more relevant and understandable. It is lavishly illustrated, often with material from the Museum of Public Relations' extensive archives and not available elsewhere. And it features more than a dozen essays by noted PR scholars commenting on Bernays's text and providing essential updates on factors that would have been science fiction to him, including social media, augmented reality, and generative artificial intelligence. Plus, in an innovative feature, QR codes at the end of every chapter can link readers of the printed version to online material that expands on the annotations. The book that launched a new industry a century ago now comes in an edition that takes everything that's happened since into account.