Language is rich in statistical regularities that capture meaningful, semantic links between words crucial for languagefluency. Words that can be combined to express meaningful ideas (e.g., drink-soda) reliably directly co-occur together,and words similar in meaning share patterns of co-occurrence (e.g. soda and milk share co-occurrence with drink). Here,we investigate whether children (4-year-olds) and adults can capitalize on these regularities to form new semantic linksbetween new and familiar words. Participants hear sentences in which new words directly co-occur or share co-occurrencewith familiar words. We then assess the formation of corresponding semantic links using an implicit, gaze-based measureand an explicit labeling measure. Results suggest that new semantic links form only from direct co-occurrence in chil-dren, and from both direct and shared co-occurrence in adults. This research is therefore uncovering the development ofmechanisms for building organized word knowledge from mere exposure to language.