In recent times, researchers of second language learning have suggested that second language learning is not simply a cognitive or linguistic issue, but is also a social, political, and cultural one (e.g., Atkinson, 2002; Firth & Wagner, 1997; Larsen-Freeman, 2007). Research on student teachers' identity (e.g., Atkinson, 2004; Day & Kington, 2008; Wenger, 1998) also stresses the importance of identity development to help students with setting goals and learning (e.g., Olsen, 2008). Therefore, this qualitative research aimed to investigate STs' identity development and how identity transfers knowledge to facilitate the learning and teaching processes. This study applied a two-semester community-based learning program involving 40 university students and 50 elementary school students in Taiwan. It was found that negotiating multiple discourses in diverse social contexts is another dimension of learning sources for student-teachers' understanding of personal values, increasing the awareness of social responsibilities, and fashioning their personal and pedagogical identities.