Modern generative grammar theory works from the assumption that the occurrence and categorical membership of sentence constituents are regulated by "licensing conditions". This study concerns itself principally with the licensing conditions of adjuncts. The theoretical framework is provided by the theory of "principles and parameters", supplemented by some innovations from the so-called "Minimalist programme". One of the book's main theses is that the licensing of adjuncts proceeds interpretatively, and thus it tests semantic and pragmatic ordering principles in addition to purely formal licensing conditions.