This study discusses functional categories in Igbo within Noam Chomsky's Minimalist Program (MP). Chapter 1 includes the introduction of the concept of functional categories and why they take central place in the study of syntax, as well as an overview of the Minimalist Program (MP). Chapter 2 discusses some historical antecedents to MP. It further discusses the economy principles of the MP as well as the place of functional categories within the overall conceptions of the MP model. Chapter 3 discusses five functional categories: Agreement, Tense, Aspect, Negation and Determiner. In chapter 4, the Igbo functional categories within the verbal domain: Tense, Aspect and Negation are discussed. Chapter 5 is an application of the theoretical issues raised in Chapter 2 to the analysis of the functional categories discussed in Chapter 3. One interesting issue discussed in Chapter 5 is the role of tone in realising some of the functional categories in Igbo. Chapter 6 discusses the functional categories within the nominal domain with much emphasis on the determiner. A revised version of the author's doctoral thesis, some of the conclusions are revolutionary, relevant to debates in the linguistic theory and in Igbo studies in particular, as well as serving as an introduction to MP.