The association between well-being and belonging differs across census-defined neighbourhoods for Ontario youth

• Individual and neighbourhood differences explained variance in well-being. • Various individual, interpersonal, and neighbourhood factors predicted well-being. • Census characteristics did not predict youth well-being. • The relationship between belonging and well-being differed across neighbourhoods. • Effect modification on the belonging/well-being association was observed. The goal of the current study was to explore the association between belonging and well-being in children and youth. Close attention was paid to the role of neighbourhoods, where associations were permitted to operate differentially across youths’ local environment, in addition to individual and interpersonal factors that may account for this effect modification. Data came from a regional survey in Southern Ontario designed to monitor well-being in young people (n = 1842; aged 9-18 years). Youth provided their forward sortation area (FSA), permitting linkage with 2021 census-defined socioeconomic status (SES) and immigration levels. Two-level multilevel models revealed statistically significant variance in well-being at neighbourhood (11.1%) and individual (88.9%) levels (plus error). A random slope was observed for belonging, suggesting that the belonging/well-being association varied across neighbourhoods. Greater well-being was observed in youth born outside of Canada, and when youth reported higher family or friend support, and neighbourhood safety and resources. Effect modification (moderation) on the belonging/well-being association was observed for gender, family support, country of birth, and neighbourhood safety. Findings affirm theoretical models suggesting that well-being in young people emerges in a complex multilevel ecology. There is an ongoing need for public health programs that are sensitive to local geographic differences, while considering the role of belonging within the proximal and distal social contexts of young people.