A study was conducted to compare the relative performance on yes-no questions of bilingual and monolingual children and to discuss the relationship of semantic development and linguistic development, both in the bilinguals and monolinguals. Eighteen English monolingual, eighteen Japanese monolingual, and eighteen Japanese-English bilingual children, three, four, and six years old, were individually asked positive questions, corresponding negative questions, positive tag questions, and corresponding negative tag questions. All subjects were tested on comprehension of spatial terms and of passive sentences to check their general level of language development. It is concluded that the English answering system is more natural to young monolingual children and that bilingual children answer Japanese negative questions using the English way but have some difficulty in answering English negative tag questions. The performance of bilingual children in the two languages was not consistent with that of monolingual children in their respective languages. There is an implication that two separate linguistic systems do not work in an additive way in bilingual children. The relationship of semantic development to linguistic development in bilingual children is not identical with the relationship in monolingual children. (SW)