The American Society of Clinical Oncology (ASCO) developed its own test -- the Medical Oncology In-Training Examination (MedOnc ITE) -- as a tool to assess trainees' knowledge of the clinical oncology subspecialty, establish consistency in educational standards across training programs, identify areas of strength and weakness in individual programs, and stimulate intraprogrammatic reading and discussion. The Accreditation Council for Graduate Medical Education Outcome Project provided additional incentive for ASCO to develop an ITE. The examination was developed in 4 years. The concept of the examination and the budget were approved by the ASCO governing board. The National Board of Medical Examiners was selected to work with ASCO. Fellowship programs were contacted to determine if they had the information technology support to hold the examination. A blueprint for the examination was developed. The test format, including the number of questions and the selection of case-based single best answers, was determined. Physician volunteers to write the questions were solicited from among program directors, various ASCO committees, and disease experts. A workshop was held to teach volunteers how to write proper case-based questions. From this pool, a smaller group of physicians was selected to develop the test and review all test questions. The final examination was developed and administered in February 2008, with scores provided to fellows and program directors in April 2008. Feedback received after the examination will be helpful for developing future MedOnc ITEs. The process ASCO went through to develop the MedOnc ITE serves as a model for other subspecialties interested in developing their own ITEs.