Teacher identity is inherently negotiable, flexible, adaptive, and conflicted (Teng, 2019). Authoring identities as a teacher of English as a foreign language (TEFL) and a researcher is complex. It is in-fluenced by internal (e.g., emotions and efficacy) and external (e.g., language policy, classroom struc-tures, and research requirement) factors. Despite the need to broaden the knowledge base on teacher identity, research around how TEFL teacher identities are forged had not received sufficient attention; much  remains  to  be  discovered  about  factors  that  evoke  changes  in  identities  and  TEFL  teachers’  commitments to teaching and research. Drawing upon notions of agency, authority, and vulnerability, and on my personal experiences, this article aims to provide new knowledge on TEFL teacher identity.TEFL teachers are the key agents who directly impact TEFL students’ learning and growth. Agency can be defined as individuals’ capacity to make their own free choices and act independently amidst cultural  and  societal  constraints  (Priestley,  Biesta,  &  Robinson,  2013).  Closely  related  to  agency  is  authority and vulnerability. Authority refers to one’s ability to make choices without hesitation, even if the teacher is in a constrained setting (Alsup, 2018); vulnerability refers to anxiety or fear that one’s decisions  might  be  incorrect,  dangerous,  or  self-defeating,  or  a  multidimensional  emotional  expe-rience  that  individuals  may  encounter  in  an  array  of  contexts  (Lasky,  2005).  The  three  notions  are  assumed to reciprocally affect TEFL teachers’ identity development and TESOL practice.