Are thoughts impossible without the words to express them? It has been claimed that this is the case for thoughts about numbers: Children cannot have the concept of exact numbers until they know the words for them, and adults in cultures whose languages lack a counting vocabulary similarly cannot possess these concepts. Here, using classical methods of developmental psychology, we show that children who are monolingual speakers of two Australian languages with very restricted number vocabularies possess the same numerical concepts as a comparable group of English-speaking indigenous Australian children.