Community water fluoridation (CWF) and its effect in reducing the burden of dental caries (tooth decay) is considered one of the 10 public health achievements in the 20th century. In the U.S., three-quarters (74.4%) of people on community water supplies have optimally fluoridated water, and each year approximately 90 communities actively consider starting or discontinuing CWF. CWF exists within the policy environment and includes actions taken by local community councils, health and water boards, and groups; state legislatures and health departments; national regulatory and science agencies; independent science entities; and professional and nonprofit organizations. Epidemiologists have been in the forefront of CWF. Experience with the past 70 years reveals that the coming decades will bring additional questions, recommendations, and challenges for CWF. The continued involvement of epidemiologists as part of multidisciplinary teams is needed in research, surveillance, peer review of studies, assessment of systematic review findings, and in the translation and communication of science findings to audiences with limited science/health literacy. This chapter’s purpose is to 1) examine how epidemiologic evidence regarding CWF has been translated into practice and policy, 2) examine how recommendations for and challenges to CWF have affected epidemiologic research and community decision-making, and 3) identify lessons learned for epidemiologists.