Papa attended Pittston elementary schools before his family moved to Long Island, NY. He attended Lawrence High School where he excelled in football and baseball. In 1940, he was selected to the New York A–State football team. Upon graduation, Pupa declined an offer to play with the New York Yankees and chose to attend the University of North Carolina on a scholarship, but his collegiate career was cut short by World War II where he served as an officer from ’42 to ’45. In 1946 Walter returned to North Carolina and continued his career as a fullback. He was named to the All-State Collegiate football team in ’46 and ’47. Pupa played in the ’47 Sugar Bowl. In 1948 he was offered a NFL contract with the Chicago Bears but he sustained a leg injury. He served as assistant coach at North Carolina before going into the business world. Walter is married to the former Babette Reichold and has three sons.