The transition from junior high school (SMP) to senior high school (SMA) is a challenge for tenth-grade students who must adjust to a new learning environment. Academic adjustment is influenced by family function, with academic self-efficacy serving as a mediating variable between the two. This study also explores the role of socioeconomic status, as students from lower economic backgrounds often face difficulties in academic adjustment. The purpose of this study was to examine the role of academic self-efficacy in mediating the relationship between family function and academic adjustment in high school students from low socioeconomic backgrounds in Jatinangor. The participants of this study were 245 tenth-grade students (138 female, 107 male, aged 14-17 years). Data were collected using the Family Assessment Device, the Academic Adjustment Scale, and the Motivated Strategies for Learning Subscale Self- Efficacy, which were adapted into Indonesian. Simple mediation analysis was conducted using Hayes' Process Macro SPSS 24. The results indicate that academic self-efficacy acted as a partial mediator in the relationship between family function and academic adjustment. These findings highlight the importance of the family's role in academic self-efficacy, which in turn enhances students' academic adjustment at school. The implications of this study emphasize the importance of involving families and strengthening academic self-efficacy to improve academic adjustment and achievement in high school students.