The increasing size of the transplant waiting list and the increasing use of expanded criteria donors places a premium on efficient use of recovered organs. Maximal organ utilization often necessitates organ sharing between transplant organizations. Optimal organ sharing requires rapid, integrated communication of donor information combined with expedited organ transportation. For more than 20 years, the United Network for Organ Sharing's Organ Center has fulfilled this task for the United States transplant community. This overview details a brief history of United States organ sharing and the role played by the Organ Center. The current scope and modes of Organ Center operations are detailed.