Marciano was an Italian-American, born and raised in Brockton, Massachusetts to Pierino Marchegiano and Pasqualina Picciuto. Both of his parents were immigrants from Italy: his father was from Ripa Teatina, Abruzzo, while his mother was from San Bartolomeo in Galdo, Campania. Rocky had three sisters - Alice, Concetta, and Elizabeth - and two brothers - Louis and Peter. When he was about eighteen months old, he contracted pneumonia, from which he almost died.
In his youth, he played baseball, worked out on homemade weightlifting equipment, and used a stuffed mail bag that hung from a tree in his back yard as a heavy bag. He attended Brockton High School, where he played on the American football and baseball teams. However, he was cut from the school baseball team because he had joined a church league, violating a school rule forbidding players from joining other teams. He dropped out of school after finishing tenth grade.
Marciano then worked as a chute man on delivery trucks for the Brockton Ice and Coal Company. He also worked as a ditch digger and as a shoemaker. Rocky was also a resident of Hanson, Massachusetts; the house he lived in still stands on Main Street.
In March 1943, Marciano was drafted into the army for a term of two years. Stationed in Wales, he helped ferry supplies across the English Channel to Normandy. After the war ended, he completed his service in March 1946 at Fort Lewis, Washington.[