The purpose of this study is to explore one bilingual person’s language development in relation to the changing environments in which she has lived. Bronfenbrenner's (1977, 1979, 1992) bioecological model provided insight as a theoretical framework in that the model emphasizes active interactions and strong interconnectedness between the individual and her surrounding environments, as well as interactions among environments (micro, meso, exo, and macrosystem). As a main data source, a two and half hour semi-structured interview was conducted with the participant, who is a Korean-English bilingual pursuing a graduate degree at an American university. The analysis of the interview data revealed that 1) the participant's developing characteristics (e.g., outgoing personality, age of language learning), 2) the changing environments (e.g., parents’ belief and philosophy, home residential location), and 3) the interactions between the participant and her environments (e.g., the participant’s intrinsic motivation and the mother’s philosophy) and interactions between inner and outer environments (e.g., school system and national educational policy) played out for the participant's reach on the current language development in Korean and English.