In 1939, the 21-year-old conductor was appointed regular conductor of the Stamford Symphony Orchestra in Connecticut. He followed previous conductor Hugo Kortschak, Dean of Music at Yale University, who had suggested Barnett for the position. At the time, Barnett was known as the “youngest professional symphony conductor in the United States.” In addition to his new post, he retained his other conducting posts in Brooklyn and New York. One of his conducting performances included an appearance at the famous 1939 New York World’s Fair, where he conducted the Federal Knickerbocker Orchestra of New York at the WPA Building on May 28, 1939, part of which was broadcast over WYNC.