Research on the internal/external frame of reference model (I/E model; Marsh, 1986) has established a strong positive correlation between academic achievement in specific subjects and corresponding academic self-concept (ASC). The model also established a negative correlation between achievement in one subject and ASC in other subjects. The model also established a negative correlation between low academic achievement and ASC. However, few studies have explored the causal relationships among achievement, ASC, self-efficacy, and mental health using an I/E model framework. This study examined the effects of domain-specific academic achievement and ASC on self-efficacy and mental health using an extended I/E model to assess the indirect effects of domain-specific academic achievement and ASC on mental health through self-efficacy. The sample included 1,079 students (318 students with learning disabilities [LDs] in grades 4–6), with the students without LDs serving as a control group. The results of the analysis indicated that students with LDs scored lower than their peers without LDs with respect to all variables except mental health. Compared with students without LDs, who engaged in social comparisons (comparing their own performance to that of their peers) across subjects, students with LDs primarily made social comparisons within mathematics. Additionally, students with LDs made dimensional comparisons (comparing their own performance across different subjects) between their mathematics achievement and their Chinese language ASC. Furthermore, the ASC of students with LDs is a direct predictor of self-efficacy and an indirect predictor of mental health through its influence on self-efficacy. The findings of this study suggest that ASC is positively correlated with self-efficacy and that self-efficacy does not directly influence mental health. This study provides empirical evidence of the effects of academic performance and self-concept on self-efficacy and mental health in students with LDs, offering insights for school psychology research and practice.