This book explores the grammar of <i>to </i>infinitives and gerundial <i>-ing</i> clauses, which is a central area at the interface of syntax and semantics, against the background of what has been called the Great Complement Shift. Over the course of six chapters, the author explores the semantic properties of constructions where the general spread of gerundial <i>-ing</i> clauses occurs at the expense of <i>to </i>infinitives. The author draws on large electronic corpora, ensuring that new perspectives are opened on the basis of authentic corpus evidence. He identifies trends of variation and change in the use of the two constructions and proposes The Choice Principle, an innovative perspective on the semantics of <i>to </i>infinitives and gerundial <i>-ing</i> complements. This book will be of interest to researchers and students working on English grammar or the recent history of English grammar.