This book explores how public policies change over time. Its central argument is that when lawmakers can process information more comprehensively, then they can react more smoothly to environmental stimuli, reducing the prevalence of incremental policy changes and the magnitude of sudden policy disruptions. The book suggests that information processing depends heavily on three factors: issue complexity, institutional capacity, and the procedures that govern decision making. Highly complex issues make information processing more difficult, so we observe more disruptions in policies addressing areas of great complexity, such as climate change, than we do from conceptually simple areas. Institutional capacity can mitigate the complexity problem by providing policymakers with the resources to engage meaningfully with new information. Finally, the book looks at how decisions are actually made and draws a distinction between deliberative mechanisms, in which policies are developed by means of debate among a small group of lawmakers, and collective mechanisms, in which the opinions of many people are aggregated, as with the stock market. When conditions are right, collective mechanisms can harness the “wisdom of crowds” to process information at very high levels. The book explores policy areas where collective mechanisms for decision making have some application and finds that major policy disruptions are remarkably rare.