The present studies examine whether and how 18-month-olds use informants' accuracy to acquire novel labels for novel objects and generalize them to a new context. In Experiment 1, two speakers made statements about the labels of familiar objects. One used accurate labels and the other used inaccurate labels. One of these speakers then introduced novel labels for two novel objects. At test, toddlers saw those two novel objects and heard an unfamiliar voice say one of the labels provided by the speaker. Only toddlers who had heard the novel labels introduced by the accurate speaker looked at the appropriate novel object above chance. Experiment 2 explored possible mechanisms underlying this difference in generalization. Rather than making statements about familiar objects' labels, both speakers asked questions about the objects' labels, with one speaker using accurate labels and the other using inaccurate labels. Toddlers' generalization of novel labels for novel objects was at chance for both speakers, suggesting that toddlers do not simply associate hearing the accurate label with the reliability of the speaker. We discuss these results in terms of potential mechanisms by which children learn and generalize novel labels across contexts from speaker reliability.