This thesis examines some phonological aspects of Dzongkha, the national language of Bhutan, through Optimality Theory (OT). In using OT to explain some language-particular phenomena, a set of constraints will be examined. These constraints, which either evaluate the markedness of output forms (markedness constraints) or disallow changes between input and output forms (faithfulness constraints) are universal, and, thus, are present in the grammars of all languages. It is the violability of these constraints along with their ranking which characterize the phonology of individual languages. The specific phenomena examined here pertain to the relationship between syllable initials and tone as well as variation connected to underlying complex onsets and coda [k]. In regard to syllable initials and tone my analysis is such that faithfulness to lexical tone dominates faithfulness to the features of these segments, such as obstruent onset voicing and syllable-initial vowel breathiness, assuming an abundance of inputs (i.e. Richness of the Base). The result is an analysis which accounts for allophonic voicing of obstruent onsets and allophonic breathiness of vowel initials, both of which occur only in the low tone. In addressing variation within Dzongkha, my consultant shows a preference for complex onset simplification, by way of either deletion or resyllabification of the initial consonant in the cluster, over faithfulness to the underlying representation. In the case of underlying coda [k] my consultant variably parses and deletes this segment. In order to account for variation, two Optimality Theoretic approaches are examined. The first approach, known as the cophonologies approach, establishes distinct phonologies within the grammar which are indexed to different morphological constructions. The second approach, Stratal OT, also establishes multiple phonologies within the grammar; however, these phonologies are limited to three levels in the grammar: stem, word, and phrase. A comparison of the analysis under each approach shows very similar analyses.