Studying how children learn words in a foreign language can shed light on how language learning changes with development. In one experiment, we examined whether three-, four-, and five-year-olds could learn and remember words for familiar and unfamiliar objects in their native English and a foreign language. All age groups could learn and remember words in their native language better than in a foreign language. Yet they all performed above chance when learning foreign words for familiar objects. Five-year-olds could also learn foreign words for unfamiliar objects and remember them for several days; with additional presentations, four-year-olds and some three-year-olds could do the same. English vocabulary size was associated with the ability to remember words learned in English but not in the foreign language. The results indicate that preschoolers are capable of learning foreign words for familiar objects, and suggest how these abilities improve during the preschool years.