ABSTRACT
The primary empirical finding of the intriguing research by Roeper and de Villiers (= RDV) is that children 3–6 years old can interpret an initial wh-adjunct in a matrix clause as having been extracted out of a CP complement with an empty specifier, but not out of a CP complement with a filled specifier, nor out of a C-less complement with a genitive or objective subject. From this, they conclude that child grammars of English resemble their adult counterparts in that complements with a filled C-specifier or with a genitive subject are barriers to the extraction of wh-adjuncts. However, the two differ in that whereas adult C-less complements with objective subjects are barriers to adjunct extraction only if the subject receives case internally (but not if it receives case externally), both types of objective-subject complement are barriers in child grammars.
