Behavioral paternalism rejects the view that individuals always do the best for themselves, by their own lights and given their constraints. A large number of systematic mistakes called biases allegedly prevent individuals from enhancing their own welfare. This general position supports an array of policy prescriptions designed to correct their decision-making. Ideal decisions are those neoclassical agents would make if they were not plagued by biases. These are the decisions of a model construct (a “puppet”). We review the leading paternalist policy proposals and their behavioral rationales. We then preview some of our criticisms and summarize the contents of subsequent chapters.