Although an increasing number of sociolinguistic researchers consider functions of voice qualities as stylistic features, few studies consider cases where voice qualities serve as the primary signs of speech registers. This article addresses this gap through the presentation of a case study of Lachixio Zapotec speech registers indexed though falsetto, breathy, creaky, modal, and whispered voice qualities. I describe the system of contrastive speech registers in Lachixio Zapotec and then track a speaker on a single evening where she switches between three of these registers. Analyzing line-by-line conversational structure I show both obligatory and creative shifts between registers that co-occur with shifts in the participant structures of the situated social interactions. I then examine similar uses of voice qualities in other Zapotec languages and in the two unrelated language families Nahuatl and Mayan to suggest the possibility that such voice registers are a feature of the Mesoamerican culture area.