Previous work indicates mutual exclusivity in word learning in monolingual, but not bilingual toddlers. We asked whether this difference indicates distinct conceptual biases, or instead reflects best-guess heuristic use in the absence of context. We altered word-learning contexts by manipulating whether a familiar- or unfamiliar-race speaker introduced a novel word for an object with a known category label painted in a new color. Both monolingual and bilingual infants showed mutual exclusivity for a familiar-race speaker, and relaxed mutual exclusivity and treated the novel word as a category label for an unfamiliar-race speaker. Thus, monolingual and bilingual infants have access to similar word-learning heuristics, and both use nonlinguistic social context to guide their use of the most appropriate heuristic.