The prefix r- in Tlacochahuaya Zapotec is most commonly a habitual aspect marker, but it also has other functions, including, with certain verbs, a progressive aspect marker. In this presentation, I describe the distribution of r- in both elicited and naturalistic contexts and compare this distribution with the use of r- in related languages. This research provides a basis for future work on the diachronic semantics of Tlacolula Valley Zapotec TAM marking.