After a stint with public relations company Alan Gordon and Associates and service in the Air Force during WWII, Cowan teamed with veteran publicist Henry Rogers to form Rogers and Cowan in 1949. The company prospered as the Hollywood studio system broke down in the 1950s and the in-house studio publicity staffs no longer routinely fed competitive gossip columnists news of the studio's contract stars. Public relations companies filled the void and Rogers and Cowan grew into one of the largest Hollywood firms in the field, with nearly 200 employees and a client roster that has included Elizabeth Taylor, Sylvester Stallone, Bruce Willis, Cybill Shepherd, Paul Newman, Clint Eastwood and Michael Keaton. In the 1980s, it expanded into serving corporate accounts. Rogers and Cowan was sold in 1991 and Cowan left the business the following year. After a two year hiatus, he opened a new firm, Cowan and Associates.