This study examined how international teaching assistants (ITAs) construct their teacher identities within an American university setting. Specifically, this study focused on the cultural influences from their native and host countries, professional mentoring practices that socialized them into teaching at an American university, and personal characteristics of the individual ITAs that shaped how the ITAs viewed themselves and their role within this particular context. This study used narrative analysis of semi-structured interviews as well as classroom-based videotaped observations which were shown to the individual participants during a follow-up interview. Using a sample of 20 participants from 12 majors who represented 15 different nationalities; each participant participated in an initial semi-structured interview which focused on their cultural background and previous teaching experiences and beliefs. Then each ITA consented to an observation of their teaching in the university classroom, leading to twenty observations, which were used to study teacher behavior and to allow the ITA to see their own self-presentational style in the classroom during the second semi-structured interview. In addition to eliciting responses to and clarifications of the video taped observations, the second interview asked follow-up questions to the first interview and concentrated on the future goals of the ITAs. The data analysis revealed the ITAs perceptions of their own teacher identities were heavily influenced by cultural, professional, and personal factors. Specifically, the cultural norms of their native culture, as well as the norms of the host cultures, were significant influences on the teacher identities as ITAs tried to adjust their educational beliefs in order to meet the expectations of the American students. Furthermore, this study showed that the ITAs needed multiple forms of mentoring in order to gain the information that they needed to become instructors in the American higher education system. This research also showed that the ITAs personalities influenced how they assessed their own teaching ability and English language proficiency. Overall most of the ITAs viewed their teaching identity as evolutionary, acknowledging room for possible improvement, even after several years of experience. Finally, this study found that ITAs who saw teaching as part of their professional future were more likely to take the time to hone their teaching skills, where as ITAs who sought other career paths were not as concerned about teacher growth. Instructional implications for ITAs, cross-cultural teachers, and teacher trainers are offered as well as suggestions for further research.