App-based language learning has gained attention for its potential to promote L2 learning beyond the classroom. However, few learners use L2 learning apps long enough to fully benefit from this learning method. Using the unified theory of acceptance and use of technology, I explored the acceptance and use of a commercially available language learning app among young English as a foreign language (EFL) learners (N = 297, aged 12-13) in a self-study context. Structural equation modeling revealed two key findings. First, the more students perceived a focal app as a useful tool and felt supported by socially important others, the more likely they were to accept the app. Second, this acceptance, combined with favorable environmental conditions, increased their actual app usage out of class. Based on these findings, pedagogical implications discuss how teachers can enhance young adolescents' app-based language learning in self-study settings.