Background:Foundations for mental health are laid early in family and school life. Family climate embraces the emotional connections within a family, and school connectedness embraces both functional and affective dimensions of relationship with school. Based on the lack of theory-driven and longitudinal epidemiological studies addressing public mental health, the aim of this longitudinal study was to investigate the associations between adolescents’ school connectedness, family climate and depressiveness in adulthood, by relying on Bronfenbrenner’s ecological theory.

Methods:The data are from the Northern Swedish Cohort, and the sample consists of 481 women and 526 men born in 1965 who participated in data collection at age 16, 21, 30 and 43. The generalized linear model method with random intercepts was used to examine the associations between family climate and school connectedness and depressiveness in adulthood.

Results: Poor school connectedness was associated with depressiveness in adulthood [β = 0.038 (95% CI 0.018–0.058) P ≤ 0.001], but poor family climate was not [β = 0.014 (95% CI −0.004–0.032)]. No difference in associations was observed between those experiencing social/material adversities in adolescence.

Conclusions: This study shows that poor school connectedness in adolescence can affect depressiveness in adulthood. The study confirms the complex processes that determine mental health and proposes a theoretical approach appealing to public mental health research. In addition, this study concludes that more life-course studies are needed to advance the knowledge of the mechanisms behind the associations between family climate and school connectedness and depressiveness in adulthood.