LaBarba began boxing around age 12 or 13 in little amateur cards held weekly at places such as the Elks Club, which were promoted by Carlo Curtiss, who had been one of World Heavyweight Champion Jess Willard's managers. "Sometimes we would have nude women at these events," he said. The first known mention of "Young Fidel" is September 17, 1920, by the Los Angeles Times, announcing a boxing/wrestling show at the Italian picnic the next day at Selig Zoo where his opponent was to be "Battling Bennie", newsboy like Fidel. Eventually, Central Junior High School boxing instructor Bob Howard saw his potential. According to an interview published January 28, 1927 in some United States newspapers, LaBarba mentioned that he defeated a boy named Dave Mariney (a.k.a. Marini) for the high school championship. Based upon this win, his friends suggested he join the amateurs, which he did. By this, he likely meant he joined the A.A.U. Fidel found it ironic that his first "official" amateur opponent was none other than Dave Mariney. This was at a semi-monthly boxing show sponsored by the Los Angeles Athletic Club (L.A.A.C). "It looked like a crime to match the two," reported the Los Angeles Times November 4, 1920. LaBarba was about four feet tall, and his opponent a foot and a half taller. "But LaBarba soon showed he knew how to take care of himself."