This thesis examines the aspectual system of Kwaḱwala, a Northern Wakashan language of British Columbia. I explore both the lexical and grammatical aspect system, and the interaction between the two systems. Instead of the traditional Vendlerian verb classes of states, activities, accomplishments and achievements, I propose that Kwaḱwala employs just three verb classes: states, processes and transitions. With regard to the grammatical aspect system, this thesis focuses on the description and analysis of the aspect suffix -x'id. I propose that this suffix is a perfective suffix which asserts only that an initial transition into an event has occurred within reference time. The thesis also offers a brief description of the contemporary Kwaḱwal...