Bilingual children's total vocabulary in each of their languages is often smaller than that of monolinguals. In their seminal study, Bialystok et al. (2010. 'Receptive vocabulary differences in monolingual and bilingual children.' "Bilingualism: Language and Cognition" 13 (4): 525-531) divided children's vocabulary into 'home' and 'school' words and found no differences in bilinguals' knowledge of 'school' words compared to monolinguals. In Study 1, we asked 292 parents and teachers to categorize words into 'home' or 'school' contexts, and in Study 2, we analyzed the vocabulary of 220 Polish-English bilingual and monolingual (English and Polish) children aged 4.5-7. The results show that bilinguals knew fewer 'home' and 'school' words than monolinguals in each language. However, bilinguals were likely to be exposed to these words either at home or at school, whereas monolinguals would hear them in both contexts. For a small subset of English words that bilinguals heard in both contexts, bilinguals showed similar performance to monolinguals. Our results provide evidence for exposure effects in vocabulary acquisition.