 A growing number of governments around the world are using behavioral science to inform public policy. So-called behavioral public policy leverages the scientific process to suggest how government decisions may or may not affect social change. Though rapidly growing, the discipline is still in its infancy, but opportunities for breaking through exist. Reporting in Behavioral Public Policy, members of the Behavioral Insights team based in London and New York review those opportunities and the challenges that persist in this arena. As part of the world's first government unit dedicated to using behavioral science, the team offers a valuable take on why behavioral science works and how it might be made to work for more governments worldwide. Though adapted to life outside of academia, behavioral public policy still faces many familiar challenges. Among them is the replication crisis that has gripped the field of psychology. Actions designed to promote social well-being could be founded on a shakier basis than originally thought. That makes critically evaluating primary evidence crucial. Along the same lines, the use of fallible proxies is problematic. Behavioral scientists should be cautious about extrapolating too far from their findings and verify the relationships that exist between variables when translating their findings to policy. Other problems are more specific to the growing field of behavioral public policy. One common concern is the lack of evidence of the long-term effects of social interventions. Whereas lab research may end with preliminary evidence gathering, behavioral public policy has only just begun. Whether successful short-term interventions carry over in the long run, apply to different cultural contexts or carry the specter of unintended consequences isn't always clear. Much work is needed to address these and other problems, but already opportunities for making gains can be identified. One of the most notable is scaling. Individuals and organizations that apply behavioral science to policy should look beyond trials as ends in themselves and consider scalability when selecting projects. That approach should extend to how other facets of behavioral science research are carried out. The traditional focus on the individual as the subject of research can be scaled to the organization or government as a primary mover and decision maker. Addressing these challenges and opportunities will require sustained effort and collaboration. How the global community of behavioral scientists steps up will determine whether policymakers will continue to view behavioral science as a reliable source of policy ideas and approaches.