This book describes the inflectional morphology of the Zamucoan family, which only consists of three languages spoken in the Chaco lowlands of northern Bolivia and southern Paraguay: Ayoreo, Chamacoco and Old Zamuco. Ayoreo and Chamacoco are considered endangered by UNESCO: the former is spoken by about 4500 people, the latter by about 2000 people. Ayoreo used to live a nomadic life in the Chaco and only sedentarized some decades ago. Nowadays there are still uncontacted groups of Ayoreo living in Paraguay. Old Zamuco, now extinct, was spoken in the 18th century in the lost Jesuit mission of San Ignacio de Samucos. The author did fieldwork on Ayoreo and Chamacoco and analyzed the data collected by the Jesuits for Old Zamuco. The first part introduces the three languages and its salient features. The rest of the book, through more than 1370 examples, describes the verb inflection (part II), the possessive inflection (part III) and the nominal suffixation of the three languages (part IV), with its typological and morphosyntactic implications. This study will be a valuable book for all those interested in South American languages, morphology, morphosyntax and typology, in the departments of linguistics and anthropology.