Equal Wings, Unequal Flapping: An Explanatory Sequential Mixed‐Methods Study of the Nonlinear Effect of L2 Grit on Achievement

ABSTRACT While the linear effect of second language (L2) grit on foreign language achievement is well documented, the nonlinear effect remains underexplored. To help address this gap, this explanatory sequential mixed‐methods study examined 220 rural Chinese junior high school students. Multilevel polynomial regression with response surface analysis revealed that (a) L2 achievement rose linearly when perseverance of effort (PE) and consistency of interest (CI) were congruent and increased together; (b) PE and CI appeared to play complementary roles in predicting L2 achievement; and (c) the nonlinear CI‐achievement association appeared to vary across different PE‐CI configurations. Qualitative interviews identified five themes that may help explain the observed nonlinear links: motivation, self‐efficacy, instructional context, emotions, and social support. Integrating quantitative and qualitative evidence, we proposed a nonlinear configural model of L2 grit and achievement that considers weighted combinations of PE and CI along with individual and contextual factors. These findings advance our understanding of the nonlinear grit‐achievement link and underscore the need for profile‐specific grit interventions.