A surge of interest in using First Language (L1) in English as Second/Foreign Language (L2/EFL) learning has recently been developed. Despite this upsurge, the concern about using L1 by teachers and students in L2/EFL classrooms is still important for researchers to consider in the field. The focus of this study is to investigate the amount and purposes of L1 use in EFL classrooms by teachers and students in two English language institutes in Iran. Responding to the research questions on the amount and purpose of L1 use, the researchers collected the data for 12 sessions (a 90-minute class) from six male and female EFL teachers aged from 25 to 30 and 155 students 19 to 25 years of age whose pre-intermediate classes were video recorded for two sessions. The findings revealed that the EFL teachers used a limited amount of L1 in the EFL classrooms though they still used it as an aid for a variety of purposes in order to improve their teaching purposes and the students' learning. The findings also indicated that using L1 facilitates students' learning in EFL classrooms, and it should not be excluded from the classroom syllabi or considered an evil in EFL classrooms.