While the expressive function of natural language has received much attention in recent years, the role grammar plays in the interpretation of expressive items has mainly been neglected in the semantic and pragmatic literature. On the other hand, while there have been syntactic studies of some expressive phenomena they do not explicitly connect to recent developments in semantics. This book bridges this gap, showing that semantics and pragmatics alone cannot capture all grammatical particularities of expressive items and that expressivity has strong syntactic reflexes that interact with the semantic interpretation and account for the mismatches between the syntax and semantics of these phenomena. The main thesis he argues for—the hypothesis of expressive syntax—is that expressivity is a syntactic feature, on a par with other established syntactic features like tense or gender. Evidence for this claim is drawn from three detailed case studies of expressive phenomena: expressive adjectives, expressive intensifiers, and expressive vocatives. These expressions exhibit some puzzling properties and by developing an account of them employing minimalist approaches to syntactic features and agreement, the author shows that expressivity, as a syntactic feature, can partake in agreement operations, trigger movement, and syntactically be selected for. This not only provides indirect evidence for the hypothesis of expressive syntax and extends the usefulness of operations on syntactic features operation beyond their traditional domains, but also highlights the hidden role grammar may play for phenomena that are often considered to be solely semantic in nature.