qualitative case study investigates the role of different types of student interaction in shaping student engagement in an EFL classroom. The study was conducted in a senior high school in Surakarta, involving one class of 36 students for classroom observations and five selected students for interviews. The research aimed to identify the types of student interactions and explore how each type influenced behavioral, cognitive, and emotional engagement. The findings revealed the presence of three main interaction types: learner-instructor, learner-learner, and learner-content. Learner-instructor interaction was the most dominant and contributed significantly to students’ focus, motivation, and understanding through teacher guidance and feedback. Learner-learner interaction encouraged collaboration and ease of communication among peers, although not all students actively participated. Learner-content interaction supported independent learning, especially when students engaged with digital materials they found enjoyable. These interactions played a vital role in shaping student engagement: behavioral engagement was influenced by the quality of peer and teacher interactions; cognitive engagement was supported by all three interaction types depending on student habits and task interactivity; emotional engagement was mainly shaped by interpersonal connections with teachers and peers. Overall, the study highlights the importance of diverse student interactions in fostering engagement in the EFL classroom.