This study investigated the relationships between students' self-efficacy and self-concept for learning languages and students' academic achievement in learning English and Chinese. 1092 eighth to eleventh graders from four Hong Kong secondary schools completed questionnaires reporting their self-efficacy, self-concept and academic results for Chinese language and English language. Results indicated that Chinese language self-efficacy and self-concept were significant predictors for Chinese language learning achievements. English language self-efficacy and self-concept predicted both students' English and Chinese learning achievements. These results provide some support for both the domain specificity of self-efficacy and the internal/external frame of reference effect. There is also support for the notion that learning English language facilitates the learning of Chinese language but not the other way around.