This thesis provides an extensive overview of the main linguistic features of coastal Dhofari Arabic, the southern-most governorate in the Sultanate of Oman, and in particular the historical Arabic-speaking communities found on its coastal plain. The study is subdivided into key sections on phonology, morphology, local and temporal relations, adverbs and particles, and syntax. It also examines some of the features identified by these sections in a separate chapter on grammaticalization theory, seeking to explain the diachronic development of function words, as well as their synchronic usage in coastal Dhofari Arabic today. A brief lexicon is given, based on the Wortatlas der arabischen Dialekte / Word Atlas of Arabic Dialects (WAD) semantic lexical categories, and supplemented with further lexical data from questionnaire and free speech recordings. The study finds that coastal Dhofari Arabic shares common features with the Arabic dialects spoken in neighbouring Yemen, Saudi Arabia, and with the northern Arabic dialects of the Sultanate of Oman. It preserves the voiced and voiceless interdental phonemes /θ/, and /ð/, retains the voiceless uvular plosive /q/, and demonstrates variable levels of the vowel raising feature Imala, which is found in other coastal communities within Arabia. Morphologically, it is typical of northern Omani Arabic dialects by its retention of more complex patterns of feminine plural agreement, both for human referents and for non-human referents. It exhibits feminine plural agreement for personal and demonstrative pronouns, and in the latter there are two separate forms of the pronoun which may indicate traces of a more complex, historical gender and number agreement system. These conservative agreement patterns are also found with verb inflection, where coastal Dhofari still retains the plural feminine inflection morphology. Unlike the northern Arabic dialects of Oman, this dialect retains only vestiges of the ablaut passive voice, similar to that of its closest neighbouring dialect of Yemeni Arabic in Wadi Ḥaḍramawt, with which there are also strong historical relations. In terms of grammaticalization, this dialect has prominent tense / aspect / and mood verbal prefixes such as the /bi-/ continuous aspect verb prefix, the /ba-/ future marker, and the particles /ʕad/ and /qad/, in common with southern Arabian dialects extending into the Saudi Arabian Nejd, and also with some of the Modern South Arabian Languages. Its use of the analytic genitive possessive linkers /haqq/ and /mal/ are notably more prominent that was previously thought, and warrant further investigation into their functional, grammatical roles.Despite the rich array of features found in this dialect, it faces strong pressure from MSA, and many of the original communities that spoke this dialect have been resettled as part of regional development since the 1970s. It is hoped therefore that this account of CDA will generate interest in its future study as well.