The decade from 1965 to 1975 was a transformative period for radiation oncology, galvanized by President Nixon’s “War on Cancer” and the 1971 National Cancer Act. The specialty underwent significant maturation, formalizing professional societies like the American Society of Therapeutic Radiologists (ASTR) and establishing the Radiation Therapy Oncology Group (RTOG) to coordinate national clinical trials. Technological leaps revolutionized cancer care, most notably the introduction of the computed tomography (CT) scanner, which enabled 3D tumor imaging and treatment planning. This era also saw the development of positron emission tomography (PET) for molecular imaging and the invention of the Gamma Knife, which established stereotactic radiosurgery as a new treatment modality. Concurrently, innovations in brachytherapy, such as after-loading techniques, improved safety and efficiency, while radiobiologists articulated the foundational “4 R’s” of radiotherapy. The chapter also highlights the crucial, yet often underrecognized, contributions of minority pioneers in medicine and oncology during this period.