The present monograph, comprising the proceedings of a conference on endemic cretinism and the thyroid in human development, is a direct extension of the Goroka conference. The symposium was sponsored by The Kroc Foundation and took place January 1972 at their headquarters - the J & R Double Arch Ranch of the Founder, Ray A. Kroc, in the Santa Ynez Valley of California. The initial papers were concerned with descriptions of endemic cretinism by investigators who have had direct experience with field studies in various parts of the world. Reports were presented from Andean South America, the Himalayas, New Guinea, Switzerland, Italy, and Central Africa. Resolution of some of the seemingly conflicting information was achieved. The conference then addressed the problems of definition, assessment, and field ascertainment of cretinism.