Guess Who 's Coming to Dinner is a 1967 comedy-drama film starring Spencer Tracy , Katharine Hepburn , Sidney Poitier , and Katharine Houghton . Guess Who 's Coming to Dinner is a 1967 American drama film starring Spencer Tracy , Sidney Poitier and Katharine Hepburn , and featuring Hepburn 's niece Katharine Houghton .