Objective: At the turn of the millennium, eating disorders (EDs) prevention was largely nonexistent. No program had reduced future onset of EDs in even a single trial, and most had not reduced ED symptoms. Sixteen years later, the ED prevention field has translated basic risk factor research into interventions, with demonstrated efficacy and effectiveness in reducing ED risk factors and symptoms, as well as future ED onset in some trials. This article reviews the aforementioned progress focusing on a model intervention (i.e., the Body Project [BP]). Method: The article is a qualitative review of the existing BP literature. Results: Although clinical psychology has struggled with bridging the research practice gap and translating efficacy and effectiveness research into clinical implementation, researchers, clinicians, and community stakeholders working with the BP have made significant progress in addressing barriers to scalability, large-scale implementation, and sustainability, reaching 3.5 million girls and young women in 125 countries. Conclusion: The successful evolution of the BP from basic research to traversing the efficacy-to-effectiveness-to-dissemination/implementation continuum has yielded significant public health impact and is thus a fitting case for this special issue commemorating the 125th anniversary of the American Psychological Association. The BP example may help others broadly implement efficacious interventions for other mental health problems.