In this study, we examined the system of case marking in two groups of German speaking children, 5 children with specific language impairment (SLI) and 5 typically developing (TD) children matched to the children with SLI on a general measure of language development. The data from both groups demonstrate high accuracy scores for structural case marking and over applications of structural cases to instances that require lexical case marking in the adult language. These results, we argue, provide evidence for the sensitivity of both TD children and children with SLI for abstract, structure-based regularities and are incompatible with accounts of SLI that posit broad syntactic deficits for these children.