Robert Justus Kleberg, Jr., rancher, the son of Alice Gertrudis (King) and Robert Justus Kleberg, was born on March 29, 1896, in Corpus Christi. He was the grandson of Richard King, founder of the King Ranch in South Texas. Despite the connotation of his name, he was the third rather than the second Robert Justus Kleberg. He began his ranching career at the King Ranch in 1916 and managed the ranch after his father's death in 1932. He was named president of the operation when it became a family corporation in 1935. In addition to the King Ranch, estimated to comprise between 800,000 and 900,000 acres in six South Texas counties, Kleberg also managed holdings in Florida, Kentucky, and Pennsylvania, and in Brazil, Argentina, Spain, Morocco, and Australia. He is credited with developing the first United States breed of beef cattle, the Santa Gertrudis, perfected over thirty years. He became known in agriculture with his development of grazing grasses. He received honorary doctorates in agricultural science from Texas A&M (1941) and in science from the University of Wisconsin (1967), where he had done undergraduate work. Under Kleberg's direction, the King Ranch developed thoroughbred racetrack winners that averaged $825,000 a year in purse money. The best known was Assault, the Triple Crown winner in 1946; Middleground and Bold Venture both won the Kentucky Derby. Kleberg had other business, banking, and railroad interests. He was married to Helen Campbell on March 2, 1926; they had one daughter. He died on October 13, 1974, in a Houston hospital and was buried at the King Ranch.