The article presents the results of a corpus-based study of the meanings of English clauses containing alternative interrogative structures (AISs). Data show that most clauses express a request to the addressee to supply the right answer to a genuine alternative or polar question. Other clauses denote the speaker’s lack of (sufficient) knowledge, unhelpful memory, wondering, uncertainty and doubt as to which of the suggested alternatives is true. Still other clauses carry alternative conditional-concessive meaning.