The 20th World Science Fiction Convention, also known unofficially as Chicon III (less frequently, Chicon II), was held August 31–September 3, 1962, at the Pick-Congress Hotel in Chicago, Illinois, United States. Because the second Worldcon held in Chicago was officially called, in its publications, the 10th Annual World Science Fiction Convention (and once as the "10th Annual Science Fiction Convention") and not Chicon, the next Chicago Worldcon held in 1962 was occasionally referred to as Chicon II, though Chicon III is the generally accepted and preferred nomenclature.