First published in 2000, this book is about sentences containing the word or, dealing primarily with sentences in which or conjoins clauses, but also some cases in which it conjoins expressions of other categories. The author aims to give an account of the discourse properties and felicity conditions of disjunction, and to use this account in explaining the behaviour of presupposition projection and of anaphora in disjunctive sentences. The author begins by giving an account of the discourse properties and felicity conditions of disjunction before turning to the presupposition projection problem. The final two chapters discuss anaphora and its interactions with disjunction.