What is wrong with today's banking system? Admati and Hellwig argue we can have a safer and healthier banking system without sacrificing any of the benefits of the system, and at essentially no cost to society. They show that banks are as fragile as they are not because they must be, but because they want to be--and they get away with it. Whereas this situation benefits bankers, it distorts the economy and exposes the public to unnecessary risks. Weak regulation and ineffective enforcement allowed the buildup of risks that ushered in the financial crisis of 2007-2009. Much can be done to create a better system and prevent crises. Yet the lessons from the crisis have not been learned.