Powered by education policy recommendations around the world, studies on different aspects of data-driven decision making (DDDM) and data literacy for teachers (DLFT) have soared in number and scope in different educational contexts. However, English language research has been quite tardy in this regard. Hence, this study aimed to investigate data types, purposes, challenges, enablers and barriers of data use among Iranian EFL teachers. For these purposes, 30 Iranian EFL teachers were selected based on the convenience sampling procedure to participate in semi-structured interviews. The participants’ responses were transcribed, coded, and analyzed based on the grounded-theory approach. This study also assessed Iranian EFL teachers’ data literacy with a researcher-made DLFT questionnaire completed by 243 participants who were selected based on the convenience sampling procedure. Furthermore, 30 EFL teachers with M.A degree and 1-5 years of teaching experience were chosen based on the convenience sampling method to participate in a DLFT workshop. Also, the effects of the DLFT intervention on the participants’ data literacy was examined through the questionnaire administrated before and after the workshop. Finally, the contribution of the workshop to EFL teachers’ professional identity (re)construction was investigated through semi-structured interviews. Collected data of the interviews were analyzed following the grounded-theory approach. The findings indicated that EFL teachers mainly used both formative and summative assessment results. In addition, they used data for accountability and different instructional purposes. Moreover, integrating data use across the curriculum was mentioned the most among the challenges of DDDM. Also, the findings revealed that language institutes’ organizational characteristics, EFL teachers’ characteristics, and data characteristics could promote and hinder DDDM. Furthermore, Iranian EFL teachers’ data literacy was shown to stand slight
