A grammar of the Ahamb language (Vanuatu) offers a description of the endangered and previously undocumented Ahamb language spoken by around 950 people. This grammatical description is one of the main outcomes of the Ahamb Language Documentation Project, which involved over 8 months of data collection with Ahamb speakers in Vanuatu and resulted in an archived collection of over 50 hours of recorded speech and other materials. This description is based on a corpus of around 22 hours of annotated Ahamb speech and other texts. This thesis starts with an introduction to the Ahamb language, its speakers and the contexts in which it is spoken. The grammatical description that follows consists of a description of Ahamb’s phonology, morphology and syntax. Ahamb’s phonology is characterised by distinctive prenasalisation in its plosives and trills. There are four contrastive trills, including the typologically rare plain bilabial trill. The vowel inventory is also relatively large compared to other related languages, with eight contrastive vowels. The description of nominals and noun phrases in Ahamb spans four chapters. Nouns in Ahamb are classified as common, personal and local. They can also be classified as alienable and inalienable, which corresponds to a structural distinction in possessive constructions involving classifiers (general and alimentary) or direct suffixation respectively. Noun phrases consist of a nominal head and various modifiers that follow it in a relatively flexible order. Verbs in Ahamb can be transitive and intransitive. Intransitive verbs are further classified as active or stative. Detransitivisation is possible with the use of prefixation or reduplication. Verbs can take a number of prefixed tense/aspect/mood/polarity modifiers and commonly feature a subject index. Subject indexes come in three paradigms with forms for all person, number and clusivity distinctions. Neutral subject indexes are used in a variety of situations and combine most freely with other preverbal modifiers. Sequential event subject indexes are used to mark the second and subsequent verb in complex clauses that encode sequential events with the same subject. Irrealis subject indexes are used in interrogatives and negative modality constructions, among others. The objects of transitive verbs can be encoded by an object pro-index, which can take four different forms. Ahamb has SVO word order. Negation can be expressed in a number of ways, including a separate prohibitive coding and a negative modality particle. Different verb-like forms can function as prepositions and deictic markers. Complementation can be expressed with or without a complementiser, corresponding to a distinction in the semantic properties of the complement taking verb. Verb serialisation has been attested on the nuclear and core level. A special type of nuclear serialisation-like construction involves coverbs – non-prototypical verb forms that are only attested in such constructions. On the core level, switch-function and ambient serialisation is attested. Subordination is possible with a large variety of conjunctions. Other complex clause types include sequential event constructions and both syndetic and asydentic coordinating constructions.