One of the central claims of the Government-Binding theory of syntax is the Extended Projection Principle, which stipulates that every clause has a subject. For those clauses which lack an overt subject, a phonologically null, or "empty", category is presumed to occupy subject positon. This book argues against the Extended Projection principle. After an analysis of infinitivals and an investigation into the nature of empty categories, the book offers a more exact and consistent notion of the different types of empty categories and demonstrates that subjects are impossible in certain German sentences.