This dissertation documents and analyzes phonetic and phonological features of Gua, an under-documented, understudied and nearly-endangered Guang language, spoken in the Eastern Region of Ghana. The language has two dialects, Anum and Boso. The data for this dissertation is from the Boso dialect spoken in the Boso community. The dissertation focuses on the properties of the sound system which includes the segmental inventory, tone, and processes such as vowel harmony, hiatus resolution, consonant assimilation and nasalization, and their interactions with other areas of the grammar. Chapter 1 provides a general introduction to Gua including a sociolinguistic survey. It also situates the scope and the relevance of the study. Chapter 2 presents the vowel inventory in the language. It discusses the different properties of the vowels including oral and nasal vowels, Advanced Tongue Root (ATR) distinctions, vowel length and vowel sequences. Acoustic measurements are provided to show the positions of oral and nasal vowels in the F1/F2 vowel space. The chapter also presents the syllable structure which consists of open syllables, no complex onsets or codas, and only nasal consonants as possible codas. Nasals may also serve as syllabic consonants. Chapter 3 presents the basic patterns of word-internal ATR vowel harmony and directionality which is robustly regressive within words, roots, and across words. Chapter 4 presents a description of cross-word harmony and demonstrates how the process is sensitive to both prosodic phrasal units as well as syntactic structure. Chapter 5 describes and analyzes consonants. Gua has voicing contrasts among stops and affricates at six places of articulation, including labio-velar stops. It also has a series of nasal consonants. The chapter presents consonant interactions that involve nasals and stops in the verbal prefix complex. These processes include nasal place assimilation, nasal assimilation and stop deletion. In Chapter 6, two processes are introduced that affect vowel realization: nasalization and vowel hiatus. Gua has a series of nasal vowels and also shows tautosyllabic nasalization of vowels triggered by either onsets or codas. This process interacts with ATR harmony, both within and across words. The chapter shows how nasal vowels are fully participatory in vowel harmony, and even though Gua lacks phonemic mid +ATR nasal vowels /ẽ, õ/, like many West African languages (Hyman 1972, Rolle 2013), these vowels can be created as allophones via the interaction of nasalization and/or ATR vowel harmony. The second section discusses the resolution of vowel hiatus (Casali 1997/2011) across morpheme and word boundaries, showing all combinations of sequences of oral vowels. The vowel hiatus resolution patterns interact with ATR harmony, leading to opacity on the surface. Chapter 7 is dedicated to the discussion of tone and tone processes. Gua is a two tone language with downstep. It also has both lexical and grammatical tone. Lexical tone distributions are tightly bound to word class in nouns, adjectives and postpositions. In verbs, tone is grammatical and there are no lexical distinctions among verb roots. Tense, mood and aspect correlate with one of three tone melodies that extend across the root. Monomoraic roots cannot host a contour tone, and how the tone melody reduces depends on the presence of a prefix. In addition, some verbal prefixes show tone polarity effects. Subject markers alternate tone based on the tone of the following tone-bearing unit. TAM prefixes display opposite tone to the following tone-bearing unit, also creating a tone polarity effect. The dissertation contributes to the description and analysis of the grammar of Guang languages. It also contributes to the typological study of phonologies of the world’s languages.