We report three experiments that explore the effect of prior linguistic knowledge on implicit language learning. Native speakers of English and native speakers of Cantonese participated in implicit learning (IL) experiments that involved different learning materials. In Experiment 1, both participant groups showed evidence of learning a mapping between articles and noun animacy. In Experiment 2, neither group showed learning of the mapping between articles and a linguistically anomalous concept (the number of capital letters in an English word or the number of strokes in a Chinese character). In Experiment 3, the Chinese group, but not the English group, showed evidence of learning a mapping between articles and a concept derived from the Chinese classifier system. It was concluded that first language knowledge affected implicit language learning, and that IL, at least when natural language learning is concerned, is not a completely unconstrained domain-general mechanism.