Many adults struggle with second language acquisition but learn new native-language words relatively easily. We investigated the role of sublexical native-language patterns on novel word acquisition. Twenty English monolinguals learned 48 novel written words in five repeated testing blocks. Half were orthographically wordlike (e.g., nish, high neighborhood density and high segment/bigram frequency), while half were not (e.g., gofp, low neighborhood density and low segment/bigram frequency). Participants were faster and more accurate at recognizing and producing wordlike items, indicating a native-language similarity benefit. Individual differences in memory and vocabulary size influenced learning, and error analyses indicated that participants extracted probabilistic information from the novel vocabulary. Results suggest that language learners benefit from both native-language overlap and regularities within the novel language.