AbstractThe Xinkan, Jicaquean, and Lencan language families are isolates. However, they show similarities in their vowel co-occurrence restrictions within morphemes. This paper compares and contrasts the harmonic patterns in each of these language families and concludes that similarities are likely due to contact between their speakers. This suggests that Xinkan, Jicaquean and Lencan speakers existed in a sort of micro-language area, a small-scale scenario of contact that shows unique indications of contact near or within the more dispersed scenarios of contact and borrowing acknowledged throughout Mesoamerica.