This thesis investigates the argument structure of Tsou, a Formosan language within the Austronesian family. The investigation studies both simplex and complex predicates as well as describes the valency groupings and alignment patterns emerging from various clausal configurations. Assuming the stance that language description should respect language-specific categories and that cross-category comparison should be justified with sufficient similarities, this thesis depicts Tsou argument structure as the interaction of a lexical predicate with the syntactic construction in which the predicate occurs. A predicate introduces event-specific participants that are to be aligned with the argument roles licensed by particular constructions. Within a construction, an argument is associated with the ACTOR/PATIENT/REFERENCE/LOCATION distinction (the four grammatical roles) and the TOPIC/NON-TOPIC contrast (the two grammatical relations). Both layers of distinctions figure prominently in determining clausal structure and the operation of syntactic processes. Disregarding any layer would inadvertently conflate the functional divisions in Tsou, leading to incomplete analyses. Adopting the constructional approach, this thesis argues that there are four major valency constructions in Tsou: Valency=0 Construction, Valency=1 Construction, Valency=2 Construction, and Valency=3 Construction. Depending on the alignment of the ACTOR/PATIENT/REFERENCE/LOCATION distinction and the TOPIC/NON-TOPIC contrast, a valency construction may instantiate various types of focus constructions. A verb may interact with different constructions and therefore illustrate alternating valency. By adopting the constructional approach, this thesis depicts alternating valency without necessarily assuming that one of the constructions involved is more basic than the other(s). On the one hand, a construction may display partial overlap of syntactic, semantic, or pragmatic properties with other constructions, but on the other hand, may carry features specific to its own. A constructional analysis is therefore capable of capturing both cross-construction similarities and construction-specific features, allowing a more comprehensive understanding of the Tsou language. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]