This book is a descriptive grammar of Aguaruna, known to its speakers as Iiniá Chicham, a Jivaroan language spoken by some 55,000 people in the northwest Peruvian Amazon. Aguaruna is typologically and historically significant because of its location in the eastern foothills of the Andes, right between the Andean and Amazonian linguistic areas. Some typologically unusual syntactic phenomena, for example in the areas of grammatical relations and case marking, make this description relevant beyond the areal context. This is the first full grammar of a Jivaroan language, covering phonology, morphology and syntax as well as addressing some issues in discourse structure. It is an important work for specialists in South American languages as well as for linguists working in more general typological fields.