Abstract: Based on the cumulative risk theory and developmental contextual theory, this study examined the mechanism underlying the effect of cumulative family risk on adolescents’ negative social adjustment, as well as the roles of trait anxiety and school connectedness in this relationship. A total of 801 high school students from two middle schools in Liaoning Province were assessed using the Cumulative Family Risk Questionnaire, the Trait Anxiety Questionnaire, the School Connectedness Scale, and the Adolescent Negative Social Adjustment Questionnaire. The results revealed significant pairwise correlations among cumulative family risk, trait anxiety, school connectedness, and negative social adjustment in adolescents. Mediation analysis indicated that: (1) The direct effect of cumulative family risk on negative social adjustment was significant; (2) Trait anxiety and school connectedness each played a separate mediating role in the relationship between cumulative family risk and negative social adjustment, while trait anxiety and school connectedness also functioned as a sequential chain of mediators. Specifically, cumulative family risk not only directly predicted negative social adjustment but also indirectly influenced it through the independent mediating effects of trait anxiety and school connectedness, as well as their chain-mediating effect.