Lanagan played college baseball at Stanford from 1897 to 1900.[1] In 1902, he married Clara Earl, a fellow member of the Stanford Class of 1900.[2]
In 1903, despite never having played football, Lanagan was selected as Stanford's head football coach, and coached the team for three years, compiling an overall record of 23–2–4.[1]
Following the 1905 season, Stanford, responding like other American universities to concerns about the violence in football, dropped football in favor of rugby from 1906 to 1917.[3][4] Despite having no knowledge of the sport, Lanagan was retained as the rugby coach, spending time in Vancouver, British Columbia and Australia to study the sport.[1][5] In his first season, the team ended with a 6–2–1 season. Lanagan remained as rugby coach for two more seasons.[1] He also served as Stanford's baseball coach from 1906 to 1907.[1][6]
Lanagan attended Stanford Law School from 1905 to 1907.[2] He resigned from coaching in 1908 to focus on his law practice.[5]
During World War I, Lanagan was a major in the United States Army, fighting in France,[2] where he contracted a lung disease that would eventually result in his death two decades later.[7]
