This book investigates context-sensitivity in natural language by examining the meaning and use of a target class of theoretically recalcitrant expressions. These expressions-including epistemic vocabulary, normative and evaluative vocabulary, and vague language ("CR-expressions")-exhibit systematic differences from paradigm context-sensitive expressions in their discourse dynamics and embedding properties. Many researchers have responded by rethinking the nature of linguistic meaning and communication. Drawing on general insights about the role of context in interpretation and collaborative action, Silk develops an improved contextualist theory of CR-expressions within the classical truth-conditional paradigm: Discourse Contextualism. The aim of Discourse Contextualism is to derive the distinctive linguistic behavior of a CR-expression from a particular contextualist interpretation of an independently motivated formal semantics, along with general principles of interpretation and conversation. It is shown how in using CR-expressions, speakers can exploit their mutual grammatical and world knowledge, and general pragmatic reasoning skills, to coordinate their attitudes and negotiate about how the context should evolve. The book focuses primarily on developing a Discourse Contextualist semantics and pragmatics for epistemic modals. The Discourse Contextualist framework is also applied to other categories of epistemic vocabulary, normative and evaluative vocabulary, and vague adjectives. The similarities/differences among these expressions, and among context-sensitive expressions more generally, have been underexplored. The development of Discourse Contextualism in this book sheds light on general features of meaning and communication, and the variety of ways in which context affects and is affected by uses of language. Discourse Contextualism provides a fruitful framework for theorizing about various broader issues in philosophy, linguistics, and cognitive science.