This chapter discusses the four linguistic isolates spoken in Mesoamerica and northern Mexico: Seri, Huave, Purépecha and Cuitlatec. Mesoamerica can be a particularly difficult region in which to determine genetic relationship since it is recognised as a linguistic area, where features have been shared across language boundaries. Huave is a language isolate spoken in towns on three peninsulas extending into the Gulf of Tehuantepec in the state of Oaxaca. There have been several proposals attempting to relate Huave to other languages and language families, primarily within in Mesoamerica. Huave can be characterized as a mildly agglutinating language, with marking on the verb for subject agreement, tense and subordination or gerundive status; nouns take possessive pronominal markers. Plurality is marked on determiners rather than on the noun itself. Huave also has several interesting phonological features, including a contrast between a plain and a palatalized series of stops, diphthongization and vowel harmony.