This study traces a middle school teacher's development through a narrative inquiry into the journal entries that she wrote while enrolled in a graduate seminar on teaching listening and speaking in English as a foreign language (EFL). It also examines the function of journal writing in her professional growth. The participant's weekly journal entries were analyzed through grounded content analysis. Additional data include an interview with the participant, her final paper, her group work products, and the researcher's field notes. Vygotskian sociocultural theory (Vygotsky 1978, 1986) was used as a theoretical framework for this study. Through journal writing as a mediational space, the teacher was able to connect theory and practice as a learner, a teacher, and a researcher. More specifically, she was enabled to externalize her learning experience as a language learner and a teacher learner. Additionally, she questioned her classroom practices in view of new understandings and conceptualizations of teaching to improve student learning, and she also developed her new understandings into research using data from her own instructional setting. However, the results indicate that her transformation of her instructional practices remained at the initial stage: whereas some evidence showed her application of her learning to her classroom practices, more often she described ideas for future instruction without evidence of implementation in the classroom. The findings of this study imply that journaling can be effectively used for fostering teacher learners' professional development and for understanding teacher learning and development. Specific implications for teacher education programs are discussed.