Competing theories of syntactic development attribute to the child differing levels of abstract knowledge, from adult-like representations to low-scope lexically-dependent schemata. We conducted a syntactic priming study to investigate whether two-year-old children possess abstract knowledge of the English auxiliary BE category. Children sometimes omit the auxiliary in spontaneous speech, and if children produce more auxiliaries after exposure to categorical as well as lexical priming, they may possess an abstract auxiliary BE category. 15 English-speaking children (2;2-3;0, M=2;8) listened to an experimenter describe two videos using sentences like the girl is swinging or the dogs are running, and were then asked to describe a novel scene. Relative to baseline, production of both auxiliary is and are increased after both lexical primes (e.g. prime = is, target = is) and within-category primes (e.g. prime = is, target = are). This result suggests that children possess abstract syntactic knowledge at an earlier age than some have claimed.