A formal National Cancer Institute Clinical Trials Cooperative Group Program was conceived in 1955 when Dr. Sidney Farber, Mary Lasker, and others approached Congress with a proposal to increase support for studies of chemotherapy of cancer. In response, Congress awarded US $5 million to the National Cancer Institute to establish the Chemotherapy National Service Center. The founders of the Cancer and Leukemia Group B, James Holland and Emil (Tom) Frei, III, envisioned that successful chemotherapy for leukemia and other hematologic malignancies could be expeditiously realized through carefully designed clinical trials executed uniformly as a cooperative effort among several institutions. In 1956, the group was designated the Acute Leukemia Group B by the Chemotherapy National Service Center Clinical Studies Panel, and Frei was elected chairman. In the ensuing 50 years, the Cancer and Leukemia Group B has expanded to national and even international membership, and its research programs have expanded to include all of the common adult solid tumors and hematologic malignancies in a multidisciplinary effort to improve the outcomes for patients with cancer and to better understand the biology of malignant disease.