Expanding on their widely discussed article on “libertarian paternalism,” Professors Sunstein and Thaler argue that people often make bad choices on diet, retirement savings, health insurance, and contributing to climate change. In their new book they examine how human beings make decisions. Recent scientific research shows that people are susceptible to cognitive biases and blunders. Because we are human, we are fallible, and because we are fallible, we can use all the help we can get. Sunstein and Thaler argue that by knowing how people think, we can design choice environments that make it easier for people to choose what is best for themselves, their families, and their society. Using colorful examples from the most important aspects of life, Thaler and Sunstein demonstrate how thoughtful “choice architecture” can be established to nudge us in beneficial directions without restricting freedom of choice. Will Wilkinson and Terrence Chorvat will raise questions about the proper place of “choice architecture” in a free society and the plausibility of “libertarian paternalism.”