The present chapter deals with some well-attested diachronic developments of body-part nouns in languages belonging to a sample of language families of South America. Body-part nouns in these languages are often implicated in the development of locative adpositions, classifiers of different sorts, and body-part prefixes (as described for Panoan languages). This chapter argues that it is possible to postulate at least four different source constructions for these developments, including incorporated nouns, derivative compounds, generic genitives, and locative compounds. As shown in this chapter, there is an intrinsic relation between these constructions and body-part nouns, and this fact, in addition to the special cognitive nature of body-part expressions, may explain why these nouns undergo the grammaticalization processes described here. Due to its widespread distribution, the recruitment of body-part nouns for the development of grammatical elements such as adpositions, classifiers, and prefixes might be considered an areal feature of South American languages.