We propose that pronominal markers in Cayuga are clitics that obey an updated version of the Tobler-Mussafia Law. Specifically, pronominal markers cannot appear at the left edge of an Intonational Phrase and undergo prosodic inversion at PF if they appear in that position at Spell-Out. This analysis has two important implications. First, we show that monomorphemic units in Cayuga are not uniformly particles, as is generally assumed. Rather, Cayuga opens up a new testing ground for the distinction between particles and clitics. Second, in order to motivate the analysis, a better understanding of the left periphery in Cayuga is developed. Specifically, the interaction between topics, wh-phrases and prosodic structure is mapped out, showing that the left periphery contains at least a Topic Phrase that dominates a Focus Phrase. Thus, this study sets the stage for a more detailed map of the clause structure in Cayuga.