Antecedent-contained deletion (ACD) constructions have been the focus of much recent literature in linguistic theory. These constructions have been instrumental in arguments against dispensing with the operation of Quantifier Raising (QR) and a level of Logical Form (LF) (e.g., May 1985; Fiengo & May 1994; Fox 1999, 2000). In fact, it has been argued that in ACD constructions, the binding principles apply at LF (e.g., Fiengo & May 1994). The present paper assesses 4- and 5-year-old children's knowledge of ACD constructions in which principles B and C are relevant. The empirical findings show that children interpret these ACD structures like adults, suggesting that they invoke the binding principles at LF, and target vP, rather than IP as the landing site for QR, as claimed for adults by Fox (2000) and others. These central properties of ACD constructions in child grammars present a challenge to learning-based theories of language development, because the input to children cannot inform them how to interpret the ellipsis site of ACD structures or which binding principle is in effect. Nevertheless, preschool children are found to have adultlike interpretations of the structures investigated here. The data are taken to provide support for the view that binding principles are part of our innate human endowment for language.