This article presents a first sketch of Karìì, a Vietic (Eastern Mon-Khmer) language spoken in upland Laos. This previously undescribed language is of special interest not only in so far as it adds to typology's sample of the world's languages, but also in so far as its complex phonological system adds to our understanding of the historical development of Vietic and Mon-Khmer, and more generally of the process of tonogenesis. Karìì syllables are defined not only in terms of segments and segmental slots, but also in terms of register ('heavy' versus 'light') and what we call 'terminance' (voiced, voiceless, checked). Register and terminance, both laryngeal features, are clearly associated with the development of lexical tone. The paper also contains a sketch of the main morphosyntactic features of the language.