Most Panoan languages have closed sets of about 30 monosyllabic forms that attach phonologically to the front of nouns, adjectives, and verbs. These forms, mainly designating body-part notions and semantic extensions of these, appear at first glance to be synchronically derived from polysyllabic body-part noun roots. This paper offers the first detailed study of the phonological, morphological, syntactic, and semantic properties of prefixation in Kashibo-Kakataibo. In contrast to other authors' analyses of Panoan prefixes, we present evidence to show that prefixes in Kashibo-Kakataibo are synchronically independent morphemes, rather than allomorphs of body-part nouns. Subsequently, we present the diachronic scenarios that can account for the perplexing formal and semantic similarities between body-part prefixes and body-part nouns in Kashibo-Kakataibo. © 2012 by The University of Chicago. All rights reserved.