We report three experiments that explore the effect of prior linguistic knowledge on implicit language learning. Native speakers of English from the United Kingdom and native speakers of Cantonese from Hong Kong participated in 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 a mapping between articles and a linguistically anomalous concept (the number of capital letters in an English word or that 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 implicit learning, at least when natural language learning is concerned, is subject to constraints and biases.