This study examines the process of Japanese language maintenance or shift among children who were exposed to Japanese and English through the "one parent-one language" approach in Melbourne. The aim was to identify factors that correlate with successful and unsuccessful cases of Japanese language maintenance of such children. The data were based on interviews with 25 Japanese mothers about their children's sociolinguistic environment and language experience. An important finding of my study is that the Japanese mother's interactional style, namely consistency in language choice and her insistence that her child should speak Japanese with her, and her commitment to engaging in regular interactions with her child in Japanese, seemed to have a strong correlation with the level of the child's Japanese language use. A parent's positive attitude and the extent of contacts with other Japanese speakers and frequency of trips to Japan did seem to help to prompt continuous development in the Japanese language. However, these features themselves did not substitute for regular shared conversations between the Japanese mother and the child, nor did they predict the level of success in the child's Japanese language development. (Contains 1 table.)