A theory of humor appreciation is advanced based on William Stephenson's play theory of mass communication and his fundamental theory of communicability. Communication pain and communication pleasure as well as the idea of "shared knowledge" are examined in relationship to humor appreciation. A method for identifying structure that accounts for one's "sense of humor" is illustrated with a Q sample (N = 54) of Gary Larson "The Far Side" cartoons. Thirty-four subjects sorted the cartoons from "most appealing" (+5) to "most unappealing (-5). Three factors emerged, from the subsequent correlation and factor analysis, representing humor factor structure that is fundamental to the theory. Humor communicability explains why some people share a sense of humor and can account for differ senses of humor. Humor communicability offers a holistic view of humor appreciation.