Oromo Language is one of the fairly well-studied languages in Ethiopia. There are various works on the phonology of the different Oromo dialects. This book is focused on the syllable structure and syllable related phonological processes of Oromo (Harar dialect) based on moraic approach. Accordingly, it attempts to describe the syllable types which are: CV, CVC, CVV, and CVVC. In view of moraic theory, the CV and CVC syllables on one hand the CVV and CVVC syllables on the other are considered light and heavy respectively. In connection with the notion of light and heavy syllables, a mono-moraic syllable is considered light, while bi-moraic and tri-moraic heavy in Oromo (Harar dialect). In these types of syllable, in addition to a vowel (short and long), a consonant after a sonority peak immediately followed by another consonants (in a cluster or gemination) bears a mora. In Harar Oromo, word-initial and final consonant gemination and cluster are not allowed. In addition to describing syllable structures from the perspective of moraic theory, the book examines syllable related phonological processes in Harar Oromo. Such phonological processes as assimilation, deletion and epenthesis.