This study explored how teachers could provide support to enhance students' out-ofclass mobile-assisted language learning (MALL) engagement. We interviewed five Korean English teachers who used "Class Card," a focal technology of this study, for their students' self-directed vocabulary learning. Additionally, students of the interviewed teachers completed a survey on their perceptions of teacher support and MALL engagement. This study has three major findings. First, the teachers adopted either a proactive or a passive approach to promoting students' out-of-class MALL engagement, which was influenced by their beliefs about whether teachers or students should be responsible for learning beyond the classroom. Second, all teachers provided orientation and behavioral support to enhance out-of-class MALL engagement, although the consistency and intensity in providing this support varied between proactive and passive teachers. Finally, students who perceived higher levels of teacher support reported greater out-of-class MALL engagement. We discuss the importance of classroom-based teacher support to enhance MALL engagement beyond the classroom as pedagogical implications.