It has long been observed that in many languages around the world possessive relations and benefactive relations are expressed by the same morphemes. There are examples of functional extension in both directions, with possessive constructions developing from benefactive ones, and vice versa. But there are also claims in the literature about the unidirectionality of this process, predicting that the development from possessive to benefactive constructions should not occur. This paper presents a detailed case study of the development of specialized benefactive expressions in Oceanic languages, where they commonly derive from expressions of attributive possession. The development starts with a possessive construction carrying a pragmatically implicated benefactive reading that gradually becomes grammaticalized and manifested in the morphosyntax of the language. This process may finally result in a benefactive construction that is syntactically and/or morphologically distinct from the expression of possession from which it originates. Syntactically, the process sets off from an object NP consisting of a noun and its modifier. In the process of grammatical change, this modifier is reanalyzed as a separate constituent, syntactically and semantically independent of the object noun. Based on data from Oceanic languages, three stages in the extension from possession to benefaction are identified. Also discussed are the contextual prerequisites for the benefactive implicature to arise in the first place.