The American College of Surgeons Oncology Group (ACOSOG) was established in 1997; it is funded by the National Cancer Institute (NCI) and American College of Surgeons (ACS) for the purpose of conducting multicenter phases II and III clinical trials in the field of surgical oncology. After eight years, ACOSOG has successfully completed seven trials and has five studies currently open to accrual for patients with brain, breast, gastrointestinal, head and neck, and lung cancers. The history of randomized controlled trials in surgery and the structure and function of ACOSOG are discussed. ACOSOG is establishing an extensive specimen bank for current and future correlative science studies, providing unique educational opportunities for surgeons in clinical research, and pursuing collaborative relationships in order to conduct trials with private industries. Also, ACOSOG has expanded its membership to include international sites, which contribute to the success of ACOSOG studies and enhance the portfolio of future protocols. The participation of general surgeons and surgical oncologists in clinical trials is essential to the improvement of treatment options for cancer patients.