O'Neill was a two-sport athlete at Williams College in Williamstown, Massachusetts.

He lettered in football in 1899, 1900, and 1901 and served as captain his senior year under coach J. J. Hazen.
The Williams College team that O'Neill captained had an overall record of 6–4 with losses to Harvard, Dartmouth, Columbia, and Army.
Even with those losses, the O'Neill-led team went on to win the 1901 Tricollegiante Football Association championship, with victories over league rivals Wesleyan and Amherst.
O'Neill lettered three times in track where he ran the 440-yard race.

As in football, he captained the track team his senior year.
O'Neill placed third in the 440 at the 1901 New England Intercollegiate Athletic Association annual championship at the Worcester Oval in Worcester, Massachusetts.
Williams College won the meet by less than a point.
O'Neill was a two-sport athlete at Williams College in Williamstown, Massachusetts. 
He lettered in football in 1899, 1900, and 1901 and served as captain his senior year under coach J. J. Hazen. The Williams College team that O'Neill captained had an overall record of 6–4 with losses to Harvard, Dartmouth, Columbia, and Army. Even with those losses, the O'Neill-led team went on to win the 1901 Tricollegiante Football Association championship, with victories over league rivals Wesleyan and Amherst. O'Neill lettered three times in track where he ran the 440-yard race.
As in football, he captained the track team his senior year. O'Neill placed third in the 440 at the 1901 New England Intercollegiate Athletic Association annual championship at the Worcester Oval in Worcester, Massachusetts. Williams College won the meet by less than a point.
Frank "Buck" O'Neill