This fundamental account of Kwaza, an unclassified language spoken by twenty five people in a remote area of Brazil’s state of Rondoˆnia, makes a superb addition in every way. Based primarily on the author’s extensive fieldwork from 1995 to 2002, it contains a thorough analysis of all aspects of the phonology, morphology, and syntax. It also provides useful commentary on varied aspects of the speakers’ culture and history, likewise hitherto barely remarked upon in any publication. Before the author’s work, documentation of this critically endangered language was limited to three brief word lists compiled in 1938, 1943, and 1984—data the author carefully takes into account. Kwaza is the speakers’ self-designation. In previous literature, the language was usually referred to as Koaia.