The Landmarks Series is a research and publications outfit funded by the Landmarks Research Foundation to publish recent outstanding doctoral dissertations on any aspect of Nigerian linguistics, languages, literatures and cultures. This study is a departer from most previous work on Yorùbá Grammar in the sense that rather than being purely a descriptive grammar; it attempts to provide a theoretical analysis of the internal and external syntax of Yorùbá nominal expressions using the Chomskyan Principles and Parameters approach to syntax. This Generative theory attempts to characterize the grammar of all natural languages in terms of a set of universal principles that all languages share, and a set of parameters along which languages may vary. The book emphasizes the empirical motivation behind major theoretical proposals in that framework, and shows how views on the nature of universal grammar and cross-linguistic variation have developed over the years as a consequence of a massive increase in cross-linguistic syntactic research.