Coulson's (2001) analysis of humor as "frame-shifting" is extended to irony and compared to other current theories of humor and irony, including Giora's (2003) graded salience model. It is argued that the effects of humor and irony often depend on a subversive relation between the initial and alternative frames, which adds to both cognitive and social meaning; understanding these effects requires consideration of the expansion of common ground (Clark, 1996) and relevance effects (Sperber & Wilson, 1986) triggered by the shift from a culturally licensed to a subversive frame. Reanalysis of several examples from recent studies in the light of these approaches shows that humor and irony, like other forms of figurative language, can serve complex communicative, social, and cognitive objectives that justify according them a central place in communication-oriented theories of language use.