The source of the idea for the study dates back to 1971 when the Hematology Study Section recommended in a position paper a study on the natural history of sickle cell disease. The Hemolytic Disease Study Group of the Division of Blood Diseases and Resources developed a detailed protocol in 1973. The National Sickle Cell Disease Advisory Committee endorsed the idea in 1975. In April 1976, the Red Cell Working Group of the Blood Diseases and Resources Advisory Committee recommended initiating the study. The National Heart, Lung, and Blood Advisory Council approved the initiative in December 1976.