The volume crystalizes the Gregerson's field work in the Kontum Province of Vietnam from 1968 to 1974, in collaboration with Rengao speakers Paul Hyum and Andre Ir. The result is a sketch grammar, a dictionary with over 6000 entries, and a text collection. Rengao is a North Bahnaric language within the Austroasiatic phylum: it features a typologically unusual tense-lax phonological contrast whose origins remain obscure, and an extensive "e;expressive"e; lexicon of onomatopoeic, ideophonic, and phonaesthemic forms integrel to the rich Rengao oral culture. The work also includes substbatial commentary on grammaticalization, borrowing and etymology.