After finishing high school, he attended the University of Pennsylvania with the intention of becoming a veterinarian but left to pursue his passion for racing Thoroughbreds.
In 1940 he obtained his trainers' license but his racing career was interrupted by service with the United States Army in the Pacific Theater of Operations during World War II.
Upon the 1946 opening of the new Monmouth Park Racetrack in Oceanport, New Jersey, Croll relocated there and became a permanent part of that facility's annual summer campaign.
At the time of her death in August 1993, she owned Croll's most famous horse, the then unraced Holy Bull.
Just a few hours before the two-year-old colt made his racing debut, Croll was notified by telephone that in her will, Rachel Carpenter had bequeathed him the seven horses under his care which included Holy Bull.