New in softcover. Hardcover was published in 2022. This volume explores the compositional semantics of clausal complementation, and proposes a theory in which clause-embedding predicates are uniformly "question-oriented", i.e., they take a set of propositions as their semantic argument. This theory opens up new horizons for the study of embedded questions and clausal complementation, and presents a successful case study on how lexical semantics interacts with syntax and compositional semantics. It offers new perspectives on issues in epistemology and the philosophy of language, such as the relationship between know-wh and know-that and the nature of attitudinal objects in general.