Diplomacy for the 21st Century recommends steps that the Department of State should embrace to take full advantage of the leading science and technology (S&T) capabilities of the United States. These capabilities provide the department with many opportunities to promote a variety of the interests of the United States and its allies in a rapidly changing world wherein S&T are important drivers of economic development at home and abroad and help ensure international security. This report assesses and makes recommendations concerning the changing environment for the conduct of diplomacy in the years ahead, with a focus on the role of S&T in the development and implementation of U.S. policies and programs. According to this report, prompt steps by the department’s leadership are essential to ensure adequate comprehension of the importance of S&T-related developments throughout the world and to incorporate this understanding within the nation’s foreign policy for the 21st century. This report also urges the adoption by the department of a broader whole-of-society approach in carrying out its responsibilities at home and abroad – extending beyond traditional interagency coordination and the narrow band of current external partners to include foundations, universities, research centers, and other groups who are extending their international reach.