Beyond achievement, educational settings offer informal supports that may be critical for child and youth mental health. However, children's educational environments have experienced significant disruption with the coronavirus pandemic. School settings offer unique opportunities to support children's mental health, but research must identify powerful points of intervention. This study examined school factors (aspirations, perceived competence, sense of belonging, and emotional engagement) as predictors of children's mental health, and the potential consequences of increasing screen time in and outside of school. Participants (N = 707) were parents and their children (6-18 years) from community and clinical settings who completed prospective surveys about children's school experiences and mental health symptoms (November 2020-May 2022). Standardized measures of depression, anxiety, irritability, inattention, and hyperactivity were collected. Structural equation modelling tested longitudinal associations between screen time, school factors, and mental health outcomes. Positive associations between each of the school factors (B = 0.14 [SE = 0.04] to B = 0.43 [SE = 0.04]) suggested they may reinforce one another. Longitudinally, sense of belonging and emotional engagement at school predicted lower severity for symptoms of depression, anxiety, irritability, and inattention (B=-0.14 [SE = 0.07] to B =-0.33 [SE = 0.10]). Greater screen time was associated with lower aspirations and perceived competence (B = - 0.08 [SE = 0.04] to B = - 0.13 [SE = 0.06]). Results suggest that school factors beyond achievement may be key correlates of child and youth mental health. While curriculum expectations emphasize academic achievement, an investment in supporting positive attitudes and aspirations at school is also warranted.