|Abstract:||This dissertation covers a broad range of the phonological and morphological phenomena found in Nuu-chah-nulth, a Wakashan language of British Columbia. Chapter 2 discusses the internal structure of Nuu-chah-nulth words and morphological properties that are related to phonological phenomena. Nuu-chah-nulth words consist of a root followed by suffixes, which must be classified into lexical and grammatical categories. It is important to understand the mechanism of combining morphemes and the characteristics of morphemes in order to find out how and/or to what extent morphology is involved in phonological alternations. Chapter 3 treats the properties of intra- and inter-segmental phonology and their consequences for linguistic theory. In particular, sections 3.1 and 3.2 look at how free combination of features drives surface alternations, especially consonant alternation. How to encode patterns, where instances of the same surface segments exhibit different behaviour depending on the morpheme in which they are found, has been a controversial issue. The approach of this thesis to this problem involves a solution consistent with a core idea of Optimality Theory, ï¿½Richness of the Baseï¿½. Chapter 4 provides additional characteristics of Nuu-chah-nulth prosody such as syllable structure, prosodic units, vowel hiatus and consonant clusters. Prosodic structures in Nuu-chah-nulth pose many interesting typological issues. I discuss basic properties of prosodic structures and their relationship with some phonological processes. Finally, chapter 5 investigates morphological processes such as reduplication and allomorphy. Nuu-chah-nulth has multiple patterns of reduplicant and base, which is not common cross-linguistically. The treatment of 9 patterns of reduplication is conducted in terms of both prosodic and metrical templates. This chapter focuses on how and to what extent phonology can be involved in the formation of words. In sum, this thesis defines how the interaction between phonology and morphology can be interpreted within Optimality Theory.