Mahre earned a spot on the U.S. Ski Team in early 1973 at age 15. He was selected to the "A" team following the 1975 season and made his World Cup debut in December 1975 at Val d'Isère, France. Two months later he competed at the 1976 Winter Olympics in Innsbruck, Austria, taking fifth in the giant slalom at age 18. He made his first podium in March with a second in a giant slalom at Copper Mountain, Colorado, and finished the 1976 World Cup season in 14th place in the overall standings. He won his first World Cup race the next season, a giant slalom at Val d'Isère in December 1976, and followed it up with a slalom win in March at Sun Valley, defeating the man who became his primary rival, the legendary Swede Ingemar Stenmark, with twin brother Steve taking third. Mahre finished ninth in the overall standings for 1977.