This authoritative reference selects, describes, and documents the impact of the most important randomized clinical trials (RCTs) in all areas of medicine and public health over the past fifty years. Contributors include clinical researchers, specialists, and knowledageable methodological experts from all domains of medicine. For each trial discussed, the coverage describes the initial state of knowledge, the political and scientific context, design choices, conflicts, impact, and long term results. The resulting text provides learning lessons for clinicians, medical researchers, methodologists, policy makers, and the scientifically literate lay public.