This study investigates the relationship between cultural adaptability and self-efficacy in second language (L2) skills among Korean college students. Using a scale developed through a synthesis of existing scales, interviews, and expert reviews, the study aims to identify which aspects of cultural adaptation are more closely linked to self-efficacy in L2 development and what cultural idiosyncrasies pose unique challenges for Korean learners of L2 English. A sample of 35 students who studied abroad for over a year in the USA, the UK, and Canada participated in the study. The results reveal considerable variability in students’ cultural adaptability across affective, cognitive, and behavioral dimensions. Notable differences were observed between groups with high and low L2 self-efficacy in specific aspects of cultural adaptation, such as minimizing cultural differences, emotional sensitivity, and avoidance of interaction. Overall, the findings suggest that affective sensitivity and behavioral resilience are more strongly associated with higher L2 self-efficacy than cognitive awareness of cultural differences. Key