The history of financial markets is full of moments in which asset prices inflate far beyond their intrinsic value. These events are commonly called bubbles, and in this book, José A. Scheinkman and other top economists offer new explanations for this phenomenon. Scheinkman discusses some stylized facts concerning bubbles, such as high trading volume and the coincidence between bubbles' implosion and increases in supply, and he develops a model for bubbles based on differences in beliefs among investors that explains these observations. Sandy Grossman and Patrick Bolton offer commentaries on Scheinkman's work, investigating factors that contribute to bubbles, such as excessive leverage, overconfidence, mania, and panic in speculative markets. Kenneth J. Arrow and Joseph E. Stiglitz add introductory material contextualizing Scheinkman's findings.