Learner autonomy is now regarded as a desirable objective in language teaching. The objective of the study was to identify ELT teachers’ strategies in promoting EFL high school students’ autonomy in vocabulary learning. Besides, this research attempts to find out the challenges that ELT high school teachers employ in promoting EFL students’ autonomy in vocabulary learning. A questionnaire and an interview were used in this study to find out the strategies adopted by the teachers in the current research as well as the challenges they face. The findings of this study revealed that English language teachers frequently promoted autonomous learners in their classrooms. They usually implemented different teaching strategies, which can be categorized into three groups involving students in a student-centered atmosphere; playing various roles in the classroom; and equipping students with the strategies to learn vocabulary. Additionally, the results demonstrated that teachers faced challenges such as learners' lack of independent learning abilities, rules and regulations implemented in schools, and teachers' lack of fundamental ways to promote autonomous learning. Finally, it is hoped that the proposed pedagogical implications will contribute to the innovation of promoting learner autonomy in vocabulary learning in the context of high school in the Mekong Delta of Vietnam.

Keywords: challenges, EFL teachers, learner autonomy, strategies