Objectives This study examined differences in fandom activities, smartphone dependency, perceived parenting styles(autonomy support and structure provision), and peer and teacher relationships between first-year middle school students in 2018 (pre-COVID-19) and those in 2021 (the second year of the pandemic). This study also examined the effects of fandom activities, smartphone dependency, and perceived parenting styles on peer and teacher relationships, the indicators of school adjustment, among first-year middle school students in 2018 and those in 2021.
 Methods Data from the first year of the 7th-grade panel (N=2,590) and the fourth year of the 4th-grade panel (N=2,275) of the 2018 Korean Children and Youth Panel Survey of the Korea Youth Policy Institute were used, and independent sample t-tests and hierarchical regression analyses were conducted.
 Results First, compared to first-year middle school students in 2018, those in 2021 exhibited significantly lower levels of fandom activities, parental autonomy support, parental structure provision, and peer relationships, along with higher smartphone dependence. Students’ relationships with teachers did not differ between the two periods. Second, autonomy support, structure provision, and fandom activities positively predicted peer relationships among first-year middle school students in both 2018 and 2021. Conversely, smartphone dependence had a negative effect on peer relationships in both years. Notably, the relative influence of structure provision on peer relationships was greater in 2021 compared to 2018. Third, autonomy support and structure provision positively predicted the relationship with teachers among students in both 2018 and 2021, while smartphone dependency had a negative effect in both periods. Fandom activities had a significant but small positive effect on students’ relationships with teachers only in 2018.
 Conclusions Implications are presented to support students transitioning to middle school in building positive relationships with peers and teachers in a rapidly changing environment.