This article examines constraints on the occurrence of null noun phrases in direct object position in Bislama, including discourse factors, syntactic factors, social factors and morphosyntactic and semantic features. The analysis identifies strong priming effects for the grammatical role and form of the antecedent. The effect of inalienable possession demonstrates the highly abstract transfer of substrate features. It is argued that key motivations for such transfer are linguistic availability and the social and cultural significance of different kinds of possession in Melanesia.