Policies that change the environment or context in which decisions are made and "nudge" people toward particular choices have been relatively ignored in health care. This article examines the role that approaches based on behavioral economics could play in "nudging" providers and patients in ways that could slow health care spending growth. The basic insight of behavioral economics is that behavior is guided by the very fallible human brain and greatly influenced by the environment or context in which choices are made. In policy arenas such as pensions and personal savings, approaches based on behavioral economics have provided notable results. In health care, such approaches have been used successfully but in limited ways, as in the use of surgical checklists that have increased patient safety and reduced costs. With health care spending climbing at unsustainable rates, we review the role that approaches based on behavioral economics could play in offering policy makers a potential set of new tools to slow spending growth.