Radiation oncology initiatives have been an integral component in the evolution of multidisciplinary research in the Cancer and Leukemia Group B. Although early studies in the Group primarily focused on chemotherapy for hematologic and pediatric malignancies, the Radiation Oncology Committee was established in 1972, reflecting the broadening scope of clinical investigation with an increased emphasis on solid tumor research. A major early contribution of the Radiation Oncology Committee was the recognition of the importance of formalized radiation quality review, which led to the development of the Quality Assurance Review Center. The committee has been instrumental in designing trials, in conjunction with our medical oncology and surgical oncology colleagues, to assess multimodality therapy. The results of many of these studies have had important implications for clinical practice. Recent efforts have explored our major research theme of treatment intensification via radiotherapy dose modulation and novel combinations of radiotherapy with sensitizing agents, with an emphasis on safely implementing advanced technologies in the cooperative group setting.