It is a long-standing puzzle why predicates like believe embed declarative but not interrogative complements (e.g., Bill believes that/*whether Mary left) and why predicates like wonder embed interrogative but not declarative complements (e.g., Bill wonders whether/*that Mary left). This paper shows how the selectional restrictions of a range of predicates (neg-raising predicates like believe, truth-evaluating predicates like be true, inquisitive predicates like wonder, and predicates of dependency like depend on) can be derived from semantic assumptions that can be independently motivated. Keywords Clause-embedding predicates • Selectional restrictions • Neg-raising 1 Introduction Certain clause-embedding predicates take both declarative and interrogative complements, as shown in (1) for know. Others take only declarative complements, as illustrated in (2) for believe, or only interrogative complements, as seen in (3) for wonder. (1) Bill knows that/whether/what Mary has eaten. (2) Bill believes that/*whether/*what Mary has eaten. (3) Bill wonders whether/what/*that Mary has eaten.