Abstract
This study investigates the mediating role of school belonging in the relationship between gender and mathematics achievement using data from the Programme for International Student Assessment (PISA) 2018 and 2022 across Finland, Norway and Sweden (N = 39,888). Structural equation modelling was employed to estimate direct and indirect associations while controlling for socioeconomic status (ESCS), with explicit comparisons conducted across countries and between the 2018 and 2022 assessment cycles. The findings reveal that gender differences in mathematics achievement are characterised by opposing pathways rather than a single directional effect. Male students report higher levels of school belonging, and school belonging is positively associated with mathematics achievement; however, the direct association between gender and achievement is negative. As a result, the positive indirect effect through belonging partially offsets the negative direct effect, leading to a non-significant overall gender effect. Importantly, these relationships vary across national contexts: the association between school belonging and achievement is strongest in Norway, weaker in Finland and not statistically significant in Sweden. Across time, indirect effects remain stable between 2018 and 2022 while the direct association between gender and achievement becomes non-significant. These findings suggest that school belonging does not operate as a uniform mechanism linking gender and academic outcomes but rather as a context-dependent factor within a set of counteracting processes influencing mathematics achievement.