<p>Learning strategies and self-concept are two important predictors of learning achievement. However, existing studies usually adopt an additive view and ignore their interplay in predicting learning achievement. This study examined three types of interplay between them in predicting English achievement: their relative importance to English achievement, the prediction of self-concept for learning strategies (i.e., deep and surface), and the prediction of self-concept for the magnitude of the effect of learning strategies on English achievement. Participants involved 2083 eighth graders (<i>M</i>_age = 13.28, <i>SD</i> = 1.09, females = 44%) studying English in sixteen secondary schools in Hong Kong. Results of structural equation modeling with latent interactions showed that: (1) self-concept outperformed learning strategies in contributing to English achievement, (2) self-concept positively predicted both deep and surface strategies, and (3) self-concept exacerbated the negative effect of surface strategies on English achievement. The study has theoretical, pedagogical, and methodological implications.</p>