The thesis is an analysis of the morphology of the Arabic dialect Tunis. Chapter one presents the relevant aspects of phonology, and chapter two is an informal outline of the main morphological pattern. Chapters three to five discuss in detail the morphology of the verb (including participles), the noun and the adjective respectively. Chapter six discusses clitics, with special reference to en-clitic pronouns. The particular contributions to previous work are as follows: (a) the data on the dialect of Tunis are set out systematically and in detail for the first time, (b) generalisations missed in previous work on Arabic [...] been allowed by certain untraditional analyses, such as taking the imperative as the underlying form of the verb, and also by the formulation of certain phonological and morphological rules, (c) a quantitative analysis of the morphological pattern based on a dictionary corpus, highlights the amount of irregularity in the system, this analysis also allows more peripheral patterns be distinguished from the central ones, the analysis is formalised in terms of the theory of 'word grammar' and constitutes the first application of this theory to a language other than English.