Between 1956 and 1959, he was musical director for Arthur Godfrey's radio program. He also worked as musical director on "The $64,000 Question" (including writing the theme music), and as the musical director of "The Jackie Gleason Show", originally called "You're in the Picture" (1961). He also organized the Westchester Youth Symphony in White Plains, New York, in 1957 (an organization he led until 1968). As a staff arranger at RCA Victor he composed and arranged music for Disney and other musicals including "Cinderella", "Alice in Wonderland", "20,000 Leagues Under the Sea", "Winnie the Pooh", "Peter Pan", and "Pinocchio". Leyden also conducted and arranged for many well-known artists including Tony Bennett, Rosemary Clooney, Don Cornell, Vic Damone, Johnny Desmond, The Four Lads, Johnny Hartman, Gordon MacRae, Mitch Miller, Ezio Pinza, Frank Sinatra, Jeri Southern, and Sarah Vaughan.