Using data from a variety of languages such as Blackfoot, Halkomelem, and Upper Austrian German, this book explores a range of grammatical categories and constructions, including tense, aspect, subjunctive, case and demonstratives. It presents a new theory of grammatical categories - the Universal Spine Hypothesis - and reinforces generative notions of Universal Grammar while accommodating insights from linguistic typology. In essence, this new theory shows that language-specific categories are built from a small set of universal categories and language-specific units of language. Throughout the book the Universal Spine Hypothesis is compared to two alternative theories - the Universal Base Hypothesis and the No Base Hypothesis. This valuable addition to the field will be welcomed by graduate students and researchers in linguistics.