Bislama allows phonetically overt and phonetically null noun phrases (NPs) in argument positions. This article explores constraints on the occurrence of null NPs in direct object position. Discourse factors (given/new status of referent, antecedent's form) and syntactic factors (antecedent's grammatical role, identification by a transitive suffix) are investigated. Morphosyntactic and semantic features that might transfer from substrate languages (referent's animacy, (in)alienable possession) and social factors (age, sex, language of education) are also examined. Strong priming effects for grammatical role of the antecedent and form of the antecedent are identified. Also salient are inalienable possession and semantic type of the verb. The effect of inalienable possession shows the highly abstract transfer of substrate features, raising questions about the modularity of grammar. It is argued that a key motivation for such transfer is not just linguistic availability, but the social and cultural significance of different kinds of possession in Melanesia.