Abstract: This thesis is a synchronic study of valence adjusting, switch-reference and ellipsis in three dialects of the Australian Western Desert language, Pitjantjatjara, Yankunytjatjara and Ngaanyatjarra (PYN). We investigate the morphosyntactic mechanisms and pragmatic motivating factors behind these phenomena. The dialects have mixed ergative and accusative case systems with productive derivational suffixing, serialisation of verbs and dependent clauses with switch-reference. We examine how these features are involved in valence adjusting and ellipsis and the situations where these occur. The material is based on a corpus of written sources, supplemented by grammaticality judgments by PYN speakers. The theoretical framework underpinning the study is that of Role and Reference Grammar (RRG), which is designed to be able to be used for the study of any language. This provides a detailed functional account, mapping syntax to semantics by way of a linking algorithm, and has constituent, operator and focus syntactic projections. Together with semantic lexical decomposition and the concept of semantic macro roles, these projections enable a study of the communicative functions and strategies for topicalising or focusing the participants in a scene or clause. Valence may refer to syntactic, semantic or macro role elements and these may not coincide; we investigate how the three relate in PYN. Furthermore the pragmatic dropping of arguments in discourse relates to focus, presupposition and shared knowledge and we distinguish this from the argument demoting and omission that necessarily occurs in valence decreasing. Valence adjusting may impact the underlying semantics; the syntactic realisation of arguments; and the assignment of macro roles and Privileged Syntactic Argument and we examine how this is achieved in PYN. It is found that the main valence-adjusting operations found in PYN are lexical rather than syntactic. Morphological derivation on nominals and intransitive verbs creates inchoative and causative verbs, depending on whether a state occurs spontaneously or is brought about by an external effector. Causation with base transitive verbs needs to be expressed syntactically and indirectly. Importantly, voice or syntactic valence adjusting is not found in the dialects. The functions of the passive are subsumed by the variance of topic and focus afforded by word order changes. Serial verbs are topic chains or complex predicates; sub-clauses may reduce the valence of the main verb, take the place of arguments or be adverbial; both actor and undergoer control is facilitated by the switch-reference ending used. Ellipsis occurs frequently, but the default assumption is that a missing argument represents third person singular. Tracking of referents is facilitated by switch-reference between active and accessible participants both within a clause and a text, and we outline how this might be represented in the presupposition. The thesis is a contribution to RRG’s representation of non-overt arguments, and sheds light not only on valence adjusting in an ergative system but also the narrative tracking of referents. Its original contribution lies in conducting an RRG analysis of valence adjusting, argument reduction, switch-reference and ellipsis in the PYN dialects. This allows us to compare the structures with those in other languages and identify areas in RRG that need to take into account structures not currently catered for by the theory. We suggest the RRG theory should be extended to take ellipsis and switch-reference structures into account and propose new ways of representing them in the constituent and semantic representations. In order to do this, webring in elements of Common Ground, Discourse Representation Theory, Centering Theory, Basic Linguistic Theory and Systemic Functional Linguistics.