Thesis: Ph. D., Massachusetts Institute of Technology, Department of Linguistics and Philosophy, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (pages 215-221).Abstract This dissertation concerns three kinds of variability that pose challenges for the compositional semantics of question-embedding sentences: (i) lexical variation among clause-embedding predicates with respect to the selection of complement types, (ii) variability in the exhaustivity of embedded questions and (iii) variability in the veridicality of embedded questions. Based on the proposal that declarative complements of question-embedding predicates are limiting cases of embedded questions, this dissertation presents a compositional-semantic a...