摘要：A lot of children in the world today acquire one language as their mother tongue and afterwards learn another language. However there are also quite a number of children who are acquiring two or more languages at the same time during their early childhood because of being raised in a bilingual family or society. Since bilingualism brings advantages to the child's future development, understanding how a bilingual child acquires the lexicon becomes a question of interest. As De Houwer (1990) suggests, children who receive primary input in each language from different interlocutors (such as a mother, father or siblings) may acquire different lexical repertoires in each language because different people talk about different things. Thus this study aimed to examine, assess and describe the sources of the differences in the receptive and productive vocabulary size of a bilingual boy in English and Turkish. The Peabody Picture Vocabulary Test III (PPVT) by Dunn & Dunn (1997) was used as a tool in measuring a bilingual boy's (3;10) productive and receptive vocabulary. The results suggested that the child performed better in English than Turkish. He produced 96% correct vocabulary in English whereas the number declined to 67% in Turkish. However the child's receptive vocabulary was almost equal in both languages. The study revealed that the frequency of exposure and differences in context cause differences in vocabulary size of a bilingual child.
