A health insurance exchange can make it possible to organize health insurance markets more efficiently and effectively than takes place today. Because so many different problems must be addressed in the insurance marketplace in order for all to have meaningful and affordable coverage, an entity like an exchange is needed to coordinate tasks and guide markets to comply with consumer protections and compete in cost-efficient ways. While not a panacea for all that ails the health system, carefully designed, an exchange can be a vehicle that facilitates and monitors the movement of the system toward many national health reform goals.