The impact of an 8.8 magnitude Chilean earthquake on elementary school students' psychosocial functioning was assessed along with exposure to adverse childhood experiences (ACEs). Skills for Life, a national school-based mental health program in Chile, routinely assesses first- and third-grade students' psychosocial functioning and classroom adaptation. Students (N = 19,627) were screened before (2009) and after (2011) the 2010 earthquake with parent- and teacher-report measures and with a parent-report of four ACEs (family psychopathology, child chronic illness, family social isolation, father absence). Earthquake exposure was categorized as mild, moderate, or severe for Chile's 15 regions. Multilevel models analyzed the unadjusted and adjusted impacts of earthquake exposure and ACEs on functioning while clustering for school- and district-level effects. In covariate-adjusted models, earthquake exposure and three ACEs were significantly associated with worsened psychosocial functioning; earthquake exposure and all four ACEs were significantly associated with worsened classroom adaptation. New family psychopathology, B = 1.90, p < .001; chronic illness, B = 2.25, p < .001; and severe earthquake impact, B = 1.29, p < .001, held the strongest negative effects on psychosocial well-being. Moderate, B = 3.04, p = .011, and severe earthquake exposure, B = 2.53, p = .047, and new family psychopathology, B = 1.99, p < .001, were associated with the worst classroom functioning 1-year postdisaster. Findings suggest that both exogenous and home-based stressors can have significant consequences for children's psychosocial functioning and classroom adaptation, and routine screening helps quantify how individual students are affected by chronic versus acute stressors.