The results of this study indicate that Grammatical specifically language impaired children and young children have problems with the syntactic representation underlying a verbal passive sentence but not with the less complex adjectival-stative passive. This new empirical evidence for the different syntactic nature of verbal and adjectival passive sentences has its implications for language acquisition and language modularity. The focus of this study is the acquisition and underlying syntactic representation of passive sentences in a subgroup of 15 `Grammatical specifically language impaired' (SLI) children (aged 9:3–12:10) and 36 younger normally developing, language ability (LA) control children (aged 5:5–8:9). In particular, the paper is concerned with the differences between a verbal and adjectival passive interpretation of the passive participle in short passive sentences. Van der Lely (1994) proposed that SLI children have a `Representational Deficit for Dependent Relationships' (RDDR). The syntactic characterization of this deficit is not altogether clear, but I propose that problems with Spec-Head relations may provide an adequate description. This proposal predicts that SLI children should be able to derive an adjectival passive but not a verbal passive representation. Active, full and short progressive passive, and ambiguous (potentially adjectival) short passive sentences were investigated. A picture pointing response paradigm, in which the child chose one of four pictures, enabled responses to be differentiated: i.e. transitive (actional), adjectival (stative), and reversal (where thematic roles normally assigned to the subject or object were reversed). The test sentences were also administered to 12 adult subjects. The study revealed that Grammatical SLI children were significantly worse at interpreting transitive verbal passive sentences than the younger LA controls. The SLI children, and occasionally the younger LA controls, may interpret an unambiguously verbal passive sentence as an adjectival-stative passive. The SLI children showed a strong preference for an adjectival interpretation for the ambiguous passive sentences. Differences in the syntactic representations of verbal and adjectival passive sentences can account for the findings. The data indicate that the Grammatical SLI children and young children have problems deriving the syntactic representation underlying a verbal passive sentence but not the less complex adjectival-stative passive. The findings from this study for Grammatical SLI children are consistent with the proposed RDDR characterized by problems in Spec-Head relations. The study provides new empirical evidence for the different syntactic nature of verbal and adjectival passive sentences and has implications for language acquisition and the modularity of language.