Sui clan exogamy can serve as a laboratory for investigation of dialect contact and immigration. The Sui people, an indigenous minority of southwest China, have marriage customs requiring that a wife and husband have different clan origins, and the wife permanently immigrates to the husband's village at the time of marriage. Due to subtle interclan dialect variation, a married woman may have different dialect features than her husband and other local villagers. This study presents an acoustic analysis of such clan-level variation in lexical tone, a sociotonetic analysis. Results show that the immigrant women maintain the tone variants of their home clan dialects to a high degree despite spending a decade or more in the husband's village, thus illustrating a case where linguistic identity is maintained in the face of close, long-term contact.