The left periphery of clausal structures has been a prominent topic of research in generative linguistics during the last decades. Closer examination of its properties unfolds a rich array of perspectives like the status of barriers for extraction and government, the articulation of the topic focus structure, the fixation of wh-scope, the marking of clausal types, the interaction of syntactic structure with inflectional morphology as well as the determination of sentence mood and illocutionary force to mention just a few. The purpose of this book is to collect different and relevant studies in this field and to give a general overview of the various theoretical approaches concerned with morphological, syntactic and semantic properties together with the diachronic development of the left periphery.