As a high school player he led his team to a state title and then played in two sports in Colgate University. He graduated from Colgate in the Class of 1918.
He returned to Colgate as a basketball coach and coached the team from 1919 to 1928 with a record of 135-52. Beginning in 1936, he served as Colgate's Athletic Director for 20 years. He was a president of Eastern Collegiate Athletic Conference (ECAC) from 1944 to 1945 and vice-president of the National Collegiate Athletic Association (NCAA) from 1942 to 1946.
The William A. Reid Athletic Center at Colgate is named in his honor.
William Reid was enshrined in the Naismith Memorial Basketball Hall of Fame in 1963 as a contributor. He is also a member of Colgate's Hall of Honor.