This study investigated issues pertaining to the properties of verbal affixes in Parakuyo that give rise to different realizations of the external and internal arguments. The study examines a range of argument realizations and alternation licensed by verbs with specific lexical-semantic, event semantic and morpho-syntactic properties introduced by the particular verbal suffixes. Thus, the study explores the interfaces of the linguistic components, mainly morphology and syntax in the Parakuyo grammar. The data were collected through focus group discussions and interviews from native speakers of the Parakuyo dialect. The theoretical framework and key perspectives employed in the study relate to key concepts underlying developments in generative syntax including Principles and Parameters theory, Minimalist Program, Distributed Morphology, Voice theory, ‘little’ v, and Cartography theory. This study employs a multi-perspective framework for investigating the lexical-semantics, event semantics and morpho-syntax of the verbal category system of affixes correlated with argument structure alternations of various kinds that necessitate exploring the interfaces between morphology and syntax that cannot be accounted for by employing any one theory. This study provides account of a range of the properties of syntactic structures in Parakuyo exemplifying the various verbal derivation affixes. Different syntactic diagnostics tests for external argument have been employed to determine whether the reference of the implicit argument can be retrieved, particularly in argument suppressing suffixes, namely the impersonal and the middle in Parakuyo. Among the diagnostic tests applied, include possibilities of modification by by-phrases, PPs modification, by-itself phrases, agentive adverbials and purpose clauses. The findings give evidence that impersonals and middles in Parakuyo do not permit an agent to occur as a subject DP or as a PP adverbial but causer, causer-event and instrumental-causer can occur in a PP modification. Both impersonal and middle verb constructions can be modified by manner-oriented adverbs. The study also relates the discussions of the verbal affixes and argument realization with other pertinent aspects like information structure and aspectual types in the events denoted by the verbs. In addition, the study examines argument-introducing affixes in Parakuyo verb constructions. These affixes are the causative, the instrumental, the dative, the motion away and motion towards affixes. The investigation of these verbal constructions demonstrates the processes of argument realization and alternation in the Parakuyo dialect. The mapping of the thematic roles for each argument introduced is done parallel to various arguments in the clauses. Furthermore, the study examines verbal suffixes in Parakuyo that do not suppress the external argument but have effect on the internal argument in various ways, including the thematic roles of such arguments. The findings suggest that both the antipassive and reciprocal in a way suppress the internal argument while reflexive constructions exhibit mixed properties towards the status of internal argument, that is, introducing the internal argument by its morphology and suppressing the same through its reflexive pronoun. Inchoative focuses on the change of state of its internal argument rendering the resultant-state. It is concluded that the multifaceted theoretical framework employed in this study is necessitated for adequately analysing the Parakuyo data.Stellenbosch University, University of Dar es Salaam, Association of African Universities