The Brooklyn native began his career as a commercial artist and also created and wrote a comic strip called "The Nebbishes" for eight years. Following the success of "A Thousand Clowns", Gardner wrote and directed "The Goodbye People", a notorious 1968 flop that focused on a man who wants to open a tropical drink stand on a beach boardwalk. It took nearly seven years before his next play, the uneven "Thieves" hit the boards and a troubled out-of-town tryout (the original leading lady quit) did not help word of mouth when it hit Broadway. Gardner's one attempt at a musical, as both lyricist and book writer for "One Night Stand" did not even officially open on Broadway although it played several preview performances in 1980. He finally hit his stride with "I'm Not Rappaport" (1984), a comedy centered on two oldsters that found its audience in NYC and went on to win the Tony Award as Best Play. His richer, autobiographical "Conversations With My Father" (1992) was also a Broadway success, fueled partly by Judd Hirsch's lead performance.
For the big screen, Gardner produced and wrote the cult hit "Who Is Harry Kellerman and Why Is He Saying All Those Terrible Things About Me?" (1971) in which Dustin Hoffman played a rock composer and singer who discovers that money doesn't buy answers to all of the mysteries of life. The feature film version of "Thieves" (1977) proved a disappointment with only Bob Fosse standing out in a cameo appearance. Gardner made his feature directorial debut with the screen version of "The Goodbye People" (1984) but while the material was clearly special to the author, audiences did not feel the same way. Only slightly more successful was his film version of "I'm Not Rappaport" (1996), which like all of Gardner's efforts had a sentimental core. In this case, though, the strong leading performances of Walter Matthau and Ossie Davis elevated the material.