Purpose: The definition of teacher identity is based on the interpretation of the meanings in educational environment and daily life experiences. The literature highlights that teacher education experiences have a central role in teacher identity construction. It is evident that exploring teacher identity is crucial during the process of teacher education. Therefore, the aim of the study was to examine the factors affecting teacher identity development in the process of teacher education. Research Methods: Sequential explanatory mixed method design was employed in this study. The aim of sequential explanatory mixed-method design is to have the qualitative data explain the quantitative results of the first phase in more detail. Findings: The findings focused on personal characteristics and teaching practices. The results of the study revealed that personal characteristics and teaching practices during teacher education are the most important factors affecting the development of pre-service teacher identity whereas media effect and close social environment are the factors, which have low effect on developing teacher identity. Implications for Research and Practice: It is observed that teacher identity hasn't been widely researched in Turkish education context. Therefore, teacher identity studies should be carried out in different population and samples. So, effects of many macro factors such as; social, political, economic ones, and micro factors such as; socio-economic background, branch differences of pre-service teachers in developing teacher identity should be investigated.