The agency was founded in 1923 by Hill Blackett and John Glen Sample, in Chicago. E. Frank Hummert joined the agency in 1927, and it was renamed Blackett-Sample-Hummert, even though Hummert was never a partner in the company. Blackett left company management, despite remaining a partner, when he was commissioned into the U.S. Navy in 1942. Hummert left the company at the end of 1943, forming Hummert Radio Productions with his wife Anne. Sample, after unsuccessful attempts to buy out the absent Blackett, announced that they would allow the firm to dissolve when their partnership agreement expired in 1944, and that he would enter a new partnership with B-S-H president H.M. "Mix" Dancer at that time. These plans were later altered to terminate the partnership earlier, on January 1, 1944, with Blackett forming his own firm and Dancer and Sample adding as a partner Clifford L. Fitzgerald, then a B-S-H vice president and director.