Particles play an essential role in the grammar of Haudenosaunee languages. Although they occur with higher frequency than any other grammatical component, their analysis has remained incomplete within both descriptive and theoretical literature, and conventional English glosses obscure their understanding for second language learners. This dissertation analyzes the semantic, pragmatic and syntactic functions of six high frequency particles that pattern together on the left periphery of Cayuga utterances in conversational discourse and oral literature. Corpus data are segmented using intonational units to identify utterance boundaries for the purpose of observing naturally occurring particle positioning. This methodology reveals a fixed organizational hierarchy of syntactic layers known for being illocutionary force operators within the assertive layers of speech acts. The work begins with oral literature, an epistemological system of knowledge transfer; in this system, particles function as narrative devices that guide the addressee's interpretation and signal culturally defined ways of managing knowledge and shared experience. Within the context of knowledge sharing this dissertation identifies Cayuga evidentials and establishes them as a distinct semantic category. Evidential particles mark sources of information, allowing speakers to distinguish between experiential or reported knowledge. Evidentials pattern tightly and predictably with other frequently occurring particles known as the assertion particle, as well as pragmatic discourse particles in the left periphery of assertive speech acts. Together, these elements compositionally create a contextual world that offers clarity to an addressee, one that also lends itself to common ground management and information structural expressions of topic and focus.