Copular verbs and copular sentences have been for many years a central issue in the theoretical discussions about the nature of (light) verbs and other grammatical categories, the ingredients of predication structures, the properties of nominal categories, agreement, and the interaction between syntax and semantics at the level of clause structure. The current research on copulas has gone beyond the investigation of what kind of objects they are, and has implications for the nature of agreement and other formal processes in syntax and morphology, as well as proposals about the types of structure building operations available in natural languages, the types of features that lexical selection is sensitive to, and the possibility that languages have access to semantically-empty elements required for the satisfaction of purely formal properties. The twelve works included in this volume illustrate the state of the art of these discussions through the analysis of detailed patterns of data from a variety of languages.