A study investigated how Samoan adults use genitive constructions in comparison with use by four young children. Results suggest that while adults and children both favor a clausal strategy of highlighting the affected object in a manipulative activity scene, Samoan children have difficulty exploiting the grammar of genitive noun phrases to encode agent roles as well. This pattern implies that children's two-constituent utterances differ from those produced by adults. In children's utterances, when an agent is not encoded as a major sentential constituent, it is likely not to be encoded as a genitive modifier and must be sought in the immediate setting or previously-mentioned absolutive noun phrases. The common and varied use of a heavily-loaded absolutive noun phrase in Samoan two-constituent utterances suggests that the internal structure of a noun phrase is a particularly central domain of grammatical and conversational competence for Samoan children to acquire. An 18-item bibliography is included. (MSE)