This introductory chapter explains the central role of psychology in revolutions, as well as the psychological perspective for understanding revolutions. The central puzzles to be solved include the puzzle of why at a deep level so little changes after revolutions, and why so many revolutions against dictatorships result in new dictatorships coming into being. There are potentially thousands of revolutions that could be the focus of this book, and the selection of the French, Russian, Chinese, Cuban, and Iranian revolutions as the focus of this book is explained. The contents of the book are briefly explained: Two chapters focus on psychological theories relevant to revolutions, three chapters on regime change, and (very importantly) three chapters on what happens in the post-revolution period. It is during this post-revolution period that typically moderates get pushed aside and extremists take over. In the final part of the book, one chapter presents a new psychological model of revolution, and another chapter addresses the question: Does human nature doom revolutions? Finally, in the Afterword, revolutions are interpreted as acts of collective creativity.