People sometimes extend invitations they don't intend to be taken seriously. We call these ostensible invitations. From a collection of spontaneous examples, we argue that they require: a pretense of sincerity by the speaker; mutual recognition of the pretense by speaker and addressee; collusion on the pretense by the addressee; ambivalence by the speaker about its acceptance; and an off-record purpose by the speaker. We describe seven techniques speakers use in fulfilling these requirements. We also show that speakers try to achieve their off-record purpose by getting addressees to recognize the expectable effects of the invitation, the situation, and the fact that they chose to extend an ostensible invitation. Finally, we argue that ostensible invitations are part of a class of ostensible speech acts, and these in turn are related to other types of nonserious language use. (Speech acts, pragmatics, off record, pretense, nonserious language use)