The period of early adolescence is characterized by dramatic changes, simultaneously affecting physiological, psychological, social, and cognitive development. The physical transition from elementary to middle school can exacerbate the stress and adversity experienced during this critical life stage. Middle school students often struggle to find social and emotional support, and many students experience a decreased sense of belonging in school, diverting students from promising academic and career trajectories. Drawing on psychological insights for promoting belonging, we fielded a brief intervention designed to help students reappraise concerns about fitting in at the start of middle school as both temporary and normal. We conducted a district-wide double-blind experimental study of this approach with middle school students (n = 1,304). Compared with the control condition activities, the intervention reduced sixth-grade disciplinary incidents across the district by 34%, increased attendance by 12%, and reduced the number of failing grades by 18%. Differences in benefits across demographic groups were not statistically significant, but some impacts were descriptively larger for historically underserved minority students and boys. A mediational analysis suggested 80% of long-term intervention effects on students' grade point averages were accounted for by changes in students' attitudes and behaviors. These results demonstrate the long-term benefits of psychologically reappraising stressful experiences during critical transitions and the psychological and behavioral mechanisms that support them. Furthermore, this brief intervention is a highly cost-effective and scalable approach that schools may use to help address the troubling decline in positive attitudes and academic outcomes typically accompanying adolescence and the middle school transition.

Brief, targeted self-affirmation writing exercises have recently been offered as a way to reduce racial achievement gaps, but evidence about their effects in educational settings is mixed, leaving ambiguity about the likely benefits of these strategies if implemented broadly. A key limitation in interpreting these mixed results is that they come from studies conducted by different research teams with different procedures in different settings; it is therefore impossible to isolate whether different effects are the result of theorized heterogeneity, unidentified moderators, or idiosyncratic features of the different studies. We addressed this limitation by conducting a well-powered replication of self-affirmation in a setting where a previous large-scale field experiment demonstrated significant positive impacts, using the same procedures. We found no evidence of effects in this replication study and estimates were precise enough to reject benefits larger than an effect size of 0.10. These null effects were significantly different from persistent benefits in the prior study in the same setting, and extensive testing revealed that currently theorized moderators of self-affirmation effects could not explain the difference. These results highlight the potential fragility of self-affirmation in educational settings when implemented widely and the need for new theory, measures, and evidence about the necessary conditions for self-affirmation success.