Abstract: Behavioral economics is influencing regulatory initiatives in many nations, including the United States and the United Kingdom. The role of behavioral economics is likely to increase in the next generation, especially in light of the growing interest in low-cost, choice-preserving regulatory tools. Choice architecture—including default rules, simplification, norms, and disclosure—can affect outcomes even if material incentives are not involved. For example, default rules can have an even larger effect than significant economic incentives. Behavioral economics has helped to inform recent and emerging reforms in areas that include savings, finance, distracted driving, energy, climate change, obesity, education, poverty, health, and the environment.