During a visit to the U.S. in 1948, an agent of Benny Goodman heard him play at a small New York music club. Not long after he returned to his home in Belgium, he received a letter inviting him to join Goodman's band while they toured in Europe. He readily accepted the invitation and joined their tours in 1949 and 1950. During the tour, Goodman was "shocked" when he learned that these tours were the first time Thielemans had earned money from his playing. Although Thielemans was hired on as a guitarist, when Goodman's group debuted at the London Palladium, he played the harmonica due to union restrictions.