Until a decade ago, no dietary supplement (DS) databases with open access for public use existed in the United States. They were needed by researchers, since half of American adults use dietary DSs and, without information on supplement use and composition, exposures could not be estimated. These articles on Challenges and Future Directions for Dietary Supplement Databases describe subsequent progress. They begin by describing why information on DSs is needed by the government and how it is used to ensure the health of the public. Current developments include: application of DS information to meet public health needs; research efforts on DS quality, efficacy, and safety (as conducted by the Office of Dietary Supplements and other federal agencies); enhanced regulatory activities implemented by the FDA Office of Dietary Supplement Programs, the FDA Office of Enforcement, and the Federal Trade Commission; and initiatives for broader development and dissemination of DS databases for commercial and public use. Other contributions in this journal supplement describe the challenges of working with DSs and the progress that has been made. Additional articles describe surveys of DS use among the general US population and also among special groups such as high supplement users, illustrating why there is a need in the United States for information on supplements. Likely directions for the future of DS science are summarized.