The distribution of null and overt subject pronouns is a prominent topic in the literature that investigates the effect of crosslinguistic influence in language acquisition. Studies on simultaneous bilingual acquisition suggest that, when a child is learning a null-subject language (like Greek) and a non-null-subject language (like English), their non-null-subject language will influence their null-subject language. Rather, studies on second language acquisition report that, when an individual with a null-subject first language is learning a non-null-subject second language, they will experience influence from their first to their second language. The present study aimed to place this investigation in a thus far unexplored context: monolingual English immersion preschools in Greece. In these preschools, children with Greek as their first language become bilingual as a result of being educated in English. 76 children (29 English-Greek successive bilingual, 23 Greek monolingual and 24 English monolingual controls) between 3;2 and 5;8 participated in the study, which explored their production of subject pronouns using a novel task. The task consisted of three practice and six test items and required children to ask and answer questions in order to find the card that the researcher had picked from a set of similar cards. All children were tested in their nurseries (in Greece and England), and successive bilingual children were tested in both their languages. The null and overt subject pronouns children produced in (both) their languages were coded and the performance of the three groups was statistically analysed. Successive bilingual children were found to produce significantly more null and fewer overt subject pronouns in English than English monolingual children. However, older bilingual children tended to perform like the monolingual controls in the English treatment. These findings suggest that, as far as successive bilingual children are concerned, crosslinguistic influence occurs from Greek to English, supporting the idea that language dominance plays an important role in determining the direction of influence, and also suggest that that language dominance might be even more important than structural factors in the context of crosslinguistic influence. The fact that successive bilingual children’s performance improves with age, indicates that crosslinguistic influence does not hinder the development and correct use of null and/or overt subject pronouns in either of a (successive) bilingual child’s language in the long run.