When Dan Carroll played on the winning Australian team at the 1908 Olympics he set a record, which has not yet been broken, of being the youngest player ever to win international honors at rugby football. In 1909, Carroll first visited America with the Australian rugby team and, when the Australians visited the West Coast again in 1912, Carroll stayed on in California and enrolled at Stanford. He was on the Stanford rugby team for four years and also played on the soccer team but, although he had been an outstanding sprinter at home, he did not make the Stanford track team. At the 1908 Olympics the Australians utilized his speed by playing him in the center, but at the 1920 Olympics Carroll himself decided, as player-coach, to play in the scrum-half position where his tactical knowledge could be put to its best use. After Stanford, Carroll furthered his education at Oxford and the Royal School of Mines in England. In 1921 he took up an appointment with Standard Oil and remained with the company until his retirement. During World War I he served as a captain in the U.S. Infantry and was awarded the Distinguished Service Cross.
On applying for US citizenship Carroll appears to have lied about his age and claimed to have been born in 1892 not his real year of birth of 1887.