This is the first comprehensive linguistic study of Bora, a typologically unusual language spoken in Colombia and Peru, the result of four decades of work among the Bora people. The language has an exceptionally high number of classifiers (over 300). These classifiers are used in various ways to carry out reference. By means of these classifiers, apposition is the primary mechanism for creating referring expressions, rather than the more cross-linguistically common mechanism of constituency. They also provide tight intersentential cohesion in discourse. The animate/inanimate distinction is pervasive, manifesting itself in the morphology, sytax, and lexicon. This volume also includes a thorough analysis of Bora grammatical and lexical tone, which has a complex system of sandhi with default tone being high, in contrast to the majority of tonal languages. The ethnographic sketch includes discussion of the unique Bora signal drums. This study will be of interest to all concerned with typological issues, South American languages and peoples, or tone studies.