This thesis attempts to implement and flesh out Prince and Smolensky's (1991) proposal for a declarative, multi-stratal model of phonology based on the quasi-connectionist notion of maximization of phonological "harmony" or well-formedness (henceforth "Harmonic Phonology"), applying this approach to a detailed analysis of the phonology of Yidiny, a language of North-Eastern Australia. In Harmonic Phonology, the phonological component of the grammar consists of a set of universal markedness principles (e.g. "prefer non-low back vowel to be rounded," or "prefer syllable to have onset"). Cross-linguistic variation is accounted for solely in terms of the ranking of such markedness statements: there are no language-specific rules or constraints. The thesis uses this framework to account for the structure of Yidiny's phoneme inventory, syllable template, and stress system, as well as a variety of alternations, including odd-syllable apocope and penultimate vowel lengthening, and demonstrates the superiority of such an analysis as compared to a rule-based account of the same phenomena.