This study investigated how Korean EFL students’ self-directed English learning abilities, learning strategy use, and the relationship between the two constructs change as they advance to upper level schools. Data were collected from 447 elementary, middle, and high school students in Seocho-gu, Seoul, using Self-Directed Language Learning Readiness (SDDLR) and a revised version of Strategy Inventory for Language Learning (SILL). The results showed that elementary school students’ SDDLR and SILL scores were significantly higher than those of middle and high school students, with no significant difference between the two groups. Among the learner factors, interest toward English study was the only factor which affected all the three groups’ SDDLR as well as SILL scores. The influence of study-abroad experience and starting age of private education was limited to the elementary school student group, indicating their short-lived effects on self-directed learning and strategy use. Lastly, there was a high or moderately high positive correlation between SDDLR and SILL in all the three groups. However, the specific relationship among subcategories of the two constructs was complicated and different among the three groups.