This volume offers the reader a wide and updated view of some of the most important approaches to three key questions in contemporary syntactic theory: What are the operations available for (syntactic) structure-building in natural languages? What are the triggers behind those structure-building operations? Which constraints operate on the structure-building operations available? All the chapters in this book aim at providing new answers to these questions on the basis of a detailed discussion of a wide range of phenomena (gapping, Right-Node-Raising, Comparative Deletion, Across-the-Board (ATB) movement, tough-constructions, nominalizations, scope interactions, wh-movement, A-movement, Case and Agreement relations, among others), and using evidence from a rich variety of languages (Brazilian Portuguese, Bulgarian, Croatian, English, German, Icelandic, Japanese, Spanish, Vata, or Vietnamese, etc.). The proposals presented clearly illustrate the shift in the locus of the explanation of linguistic phenomena that characterizes contemporary linguistic theory. A shift, in many cases, from a model which relied on properties of systems external to narrow syntax (such as the Lexicon or the PF component), to one which relies on properties of the structure-building mechanisms available.