This article reports on research into self-directed English leaning of Korean university students, focusing on their motivation and metacognition. In general, university students in Korea undertake independent learning to improve their English competence outside the classroom, rather than relying on English courses provided by their universities. Although much of their English learning is self-directed, little has been known about how they carry out their out-of-class English learning. To obtain a better understanding of their self-directed learning, this study, employing a qualitative approach, analyzed reflective journals written by 25 university students during one semester. From the analysis, students’ motivation and metacognition emerged as important themes involved in the students’ self-directed learning. The findings of this study suggest that student motivation continuously ebbs and flows as a result of its complex interrelationship with contextual factors. In addition, it was found that students’ metacognitive knowledge played a crucial role in directing their out-of-class learning as students adopted learning strategies based on their metacognitive knowledge, which was again formed and revised in the course of their learning process. Finally, this article presents suggestions for promoting students’ self-directed English learning.