Learning is often accompanied by a subjective sense of confidence in one’s knowledge, a feeling of knowing what you know and how well you know it. Subjective confidence has been shown to guide learning in other domains, but has received little attention so far in the word learning literature. Across three word learning experiments, we investigated whether and how a sense of confidence in having acquired a word meaning influences the word learning process itself. First, we show evidence for a confirmation bias during word learning in a cross-situational statistical learning task: Learners who are highly confident they know the meaning of a word are more likely to persist in their belief than learners who are not, even after observing objective evidence disconfirming their belief. Second, we show that subjective confidence in a word meaning modulates inferential processes based on that word, affecting learning over the whole lexicon: Learners who hold high confidence in a word meaning are more likely to use that word to make mutual exclusivity inferences about the meaning of other words. We conclude that confidence influences word learning by modulating both information selection processes and inferential processes and discuss the implications of these results for word learning models.