| This study investigates the challenges and perceptions of in-service elementary Science teachers regarding teachers’ self-efficacy when using English as the Medium of Instruction (EMI). With an increasing number of EMI in schools that do not speak English such as Indonesia, teachers’ roles in facilitating content delivery in English is imperative. Despite its benefits in preparing students for global communication and fostering bilingual competencies, EMI implementation presents challenges, particularly in teacher proficiency and self-efficacy. Employing a qualitative approach, this research explores the challenges faced by nine science teachers in an EMI context and their perceived self-efficacy in student engagement, instructional strategies, and classroom management. The data was collected using questionnaires developed by Tschannen-Moran and Hoy (2001), followed by semi-structured interviews. The data from the questionnaire and interviews were analyzed using a thematic analysis framework (Braun & Clarke, 2021). The findings of the study reveal significant challenges, including the teachers’ limited English proficiency, resources, and classroom interactions. However, the findings also highlight the perceived teachers’ self-efficacy, specifically the strategies in which they create student engagement, critical thinking, and collaboration. The result of teachers’ self-efficacy from the aspect of student engagement shows that teachers believe that they can support and motivate students by collaborating with students’ parents in a positive way. The efficacy of teachers’ instructional strategies shows that teachers can manage their classrooms by giving clear instructions and applying teaching strategies based on students’ level of understanding. In the aspect of teachers’ self-efficacy in classroom management, it shows that teachers believe that they can manage their students and the classroom. Some strategies also applied by the teachers are the importance of teacher training, institutional support, and self-efficacy development in enhancing EMI practices. In conclusion, this study underscores the significance of pre- assessments in facilitating tailored instructional approaches that align with students’ readiness levels. Employing student and teacher centered teaching methods is essential, as these methods address the diverse learning needs of each student. Additionally, it is necessary to provide personalized support for student success while cultivating inclusive classroom environments that promote active participation and collaboration among all learners. Together, these strategies are critical for delivering effective Science education learning in EMI settings, enhancing the overall student learning outcomes. |