Cappelletti attended Monsignor Bonner High School in Drexel Hill, Pennsylvania. As a senior tailback at Penn State, he gained 1,522 yards on 286 carries scoring 17 touchdowns as the Nittany Lions rolled to an undefeated season. He was awarded the 1973 Heisman Trophy, Maxwell Award, the UPI College Football Player of the Year, the Walter Camp Award, the Chic Harley Award, as well as receiving All-America honors. In his two-year running-back career, he gained over 100 yards in thirteen games and had a career total of 2,639 yards and twenty-nine touchdowns for an average of 120 yards per game and 5.1 yards per carry. Cappelletti's Heisman acceptance speech, where he dedicated his award to his dying brother, Joey, is one of the most memorable in the history of college sports.
The relationship between Cappelletti and his younger brother, Joey, who died of childhood leukemia on April 8, 1976, was made into a television movie in 1977 called Something for Joey; Cappelletti was played by Marc Singer. The movie was based on the book of the same name written by Richard E. Peck and chronicled the bond between the two brothers as Cappelletti supported his young brother through his battle against cancer.
During Cappelletti's senior season, Penn State was scheduled to play the West Virginia Mountaineers in a late October afternoon match. The morning of the game, Cappelletti asked Joey what he wanted for his upcoming 11th birthday. Joey replied "I want you to score three touchdowns for me. No, four."
In Something for Joey a shocked Cappelletti is seen confiding to a teammate: "How am I going to score four touchdowns?"
At the end of the 1st half, Cappelletti had scored 3 touchdowns, well on his way to four. But head coach Joe Paterno did not like to run up the score against opponents, so when the game resumed after halftime, Paterno told Cappelletti he would be on the bench. Cappelletti quietly took his seat on the bench, without telling Paterno of Joey's wish.
Late in the 3rd quarter, one of Cappelletti's teammates told Paterno of Joey's wish. On Penn State's next possession, Paterno shouted "22", and Cappelletti took the field. Cappelletti scored his 4th touchdown on the same possession, and pointed to Joey as he ran off the field.
As the undefeated 1973 team was honored at halftime in the 2013-2014 Penn State football season home opener against Eastern Michigan University on September 7th, 2013, Heisman Trophy-winning running back John Cappelletti received special recognition -- his No. 22 jersey will be retired by Penn State Football. It's the first number to be retired by any Penn State sport.
Cappelletti is married with four sons and now resides in Laguna Niguel, California, with wife, Betty (née Berry). His sister-in-law is the daughter of Heisman Trophy winner, Alan Ameche.