The acquisition of Bantu noun class prefixes has long been an issue of theoretical interest, due in part to the large number of gender classes. In contrast, the acquisition of Bantu nominal agreement has received little attention. Given findings from other languages, one might expect the phonologically transparent system of Bantu agreement to be mastered early and easily. However, the recent discovery that Sotho languages permit null prefixes under certain grammatical conditions raises the possibility that learning nominal agreement might be more challenging than originally thought. The goal of this study was therefore to assess Sesotho-speaking 2-3-year-olds' acquisition of nominal agreement as a function of full versus reduced noun class prefixes. Although the children exhibited early phonological underspecification, they otherwise represented nominal agreement with little problem, whether the noun class prefix was produced or not. The implications for learnability, and the development of lexical representations more generally, are discussed.