How L1 Influence Changes with Regard to L2 Proficiency Increase ?

The research is being carried out in the form of seven in-depth longitudinal case studies with EFL teachers at different levels of teaching experience. Research data are being collected via a variety of ethnographic research instruments, namely classroom observations and field notes, video recordings of school lessons, and in-depth interviews and video-triggered reflective dialogues with the teachers and students and teacher’ action research in L1 influences in schools of Iran. The research is significant in suggesting that, this is the crucial similarity measures which determine the stability of L1 influence.