Owing to the importance of learner autonomy (LA) and considering the prominent role of teachers in this respect, the present study investigated: (1) Iranian English as a foreign language teachers' practices for promoting high school students' autonomy, (2) possible differences among teachers' practices with different educational degrees, levels of experience, and gender, and (3) factors which, in teachers' opinion, affect their practices for promoting LA. To this purpose, 80 randomly selected teachers answered Chang's (2007. "The Influence of Group Processes on Learners' Autonomous Beliefs and Behaviours." "System" 35 (3): 322-337.) questionnaire. The statistical analysis revealed no significant difference between the experienced/inexperienced and BA/MA groups. However, female teachers were found to outperform males in using specific strategies. Moreover, the interviewed teachers believed that their practices could be affected by a number of factors such as resources, teacher training, freedom in syllabus and tests, as well as students', parents', and principals' expectations. The findings of this study provide functional pedagogical implications for language teachers and teacher educators.