Cass Sunstein reviews Richard Thaler's new book, The Mischievous Science. Thaler's book is an account of the struggle to bring the discipline of economics down to earth. He aims to change the way people think about the field, themselves and the world. Sunstein's review discusses much of the history of behavioral economics. He mentions that while scientists such as Elke Weber have made much progress on the subject of answering questions about heterogeneity in human behavior, there is still much to learn. The focus of future research should be to bridge this gap and find ways to make reliable predictions about behavioral findings.