Background: To combat stereotype threat, several school-based field trials have leveraged self-affirmation theory (Steele & Liu, 1983; Liu & Steele, 1986), wherein affirming one's important beliefs and values can buffer against identity threats. Self-affirmation theory posits that individuals are motivated to maintain a positive overall self-view. When one's self-competence is threatened (e.g., being negatively stereotyped in school), it helps to have opportunities to reflect on sources of self-worth (e.g., being a family member, enjoying sports, being creative) beyond the threatened aspect of the self, (Cohen & Sherman, 2014; Steele, 1988). Cohen et al. (2006) reported that brief writing exercises, which prompted students to reflect on and write about their core beliefs and values, reduced the Black-White grade-point-average (GPA) gap among seventh-grade students by 40%. Sherman et al. (2013) reported similar impacts for Latinx middle-school students. Longitudinal studies, also focused middle-school students, have revealed enduring impacts for students of color on middle and high school GPA (Borman et al., 2016; Borman et al., 2018; Borman et al., 2021), on-time high school graduation rates (Borman et al., 2021), and college enrollment (Goyer et al., 2017). However, Hanselman et al. (2017) caution that self-affirmation effects may be sensitive to school context, which can vary across schools. Purpose/Research Questions: This project provides a direct replication of these prior efforts at an unprecedented scale, spanning 8 districts and 16 schools, and answers three research questions (RQs): 1. Does assignment to the self-affirmation intervention impact seventh-grade students' GPAs and D and F grades? 2. Are these impacts moderated by students' race/ethnicity? 3. To what extent does engaging in self-affirming writing--as induced by the intervention--predict academic performance? Setting: The sample includes 16 schools in 8 districts across 6 states and took place in academic year 2020-21. A total of 2,398 students were randomized to experimental conditions (1,199 to treatment and 1,199 to control) and, after data attrition, the final analytical sample included 1,487 students (745 treatment and 742 control). The overall and differential attrition rates meet the What Works Clearinghouse (2022) standards for "low" attrition and a minimal risk of bias. Participants: The analytical sample of grade 7 students is diverse, with 71% classified as economically disadvantaged, 20% African American, 33% Latinx, 39% White, 3% Asian, and 5% multi-racial/ethnic. Intervention: The intervention comprises three or four brief in-class writing exercises where students reflect on personally important values. Control students engage in similar writing activities on neutral topics. Teachers distributed intervention materials without knowledge of study hypotheses or students' assignment to condition. Students took approximately 15 minutes to complete each exercise and wrote an average of 66 words when responding to the first prompt. The average completion rate across exercises was 78%. Research Design: For this multisite randomized controlled trial we randomly assigned students to experimental conditions within school and race/ethnicity blocks. Data Collection and Analysis: To estimate the intention-to-treat (ITT) impacts (RQ1), we specified a two-level random intercept model (students nested within schools) Yij=?+?(Treatmentij)+??Xij+uj+?ij In this model, ? is the coefficient representing the overall impact of self-affirmation for all student groups, and ?? Xij represents the covariates (i.e., potentially threatened status [0 = White, Asian, American Indian, and multiracial/ethnic; 1 = Black, Latinx]), prior grade 6 GPA, special education status, free or reduced-price lunch status, English language learner status). To evaluate whether students' membership in a potentially stereotype-threatened group (i.e., African American and Latinx students) moderated intervention effects (RQ2), we fit the same multilevel models, but added a treatment-by-potentially threatened status interaction term. To estimate the impact of self-affirming writing, we used an instrumental variables (IV) model. To perform this analysis, the following multilevel models were estimated using two-stage least squares (2SLS) regressions: SelfAffirm=?_0+?_1 Treatment+?_2 Treatment*Threatened+?X+uj+?ij Y_((ij))=?_0+?_1 SelfAffirm+?_2 SelfAffirm*Threatened+ ?X+uj+?ij The coefficient ?_2, is the interaction effect of the TOT by students' threatened status. Covariates were included in both stages of the instrumental variables regression, as before, to improve precision. Findings: Analysis of pre-intervention data demonstrates that the analytic treatment and control group samples are statistically equivalent with respect to demographic, GPA, and D and F grade counts (see Table 1). Impact analyses indicate that being assigned to receive the self-affirmation intervention did not have statistically significant main effects on academic performance (see Table 2) as expected. Because only Black and Latinx (potentially threatened) students tend to benefit, the statistically significant interaction effect for D and F grades shown in Table 3 is expected. As Figure 1 illustrates, potentially threatened students receiving intervention realized reductions in D and F grades, while their control-group peers did not. Though the moderating effects of treatment for potentially threatened students on the GPA outcome (see Table 3) is in the expected direction, this outcome did not reach statistical significance. The multilevel 2SLS regression analyses (see Table 4) reveal that the interaction between students' threatened status and the estimated probability of engaging in self-affirming writing is a statistically significant predictor of D and F grades. Specifically, as the predicted probability of self-affirming writing induced by treatment increases, potentially threatened students experience fewer D and F grades while non-threatened students do not (see Figure 2). Indeed, the interaction effect for engaging in self-affirming writing--the effect of the treatment on the treated--is twice as large as that found for assignment to receive the self-affirmation exercises. Conclusions: The results for the 2021-22 cohort, revealed far more promising outcomes for students vulnerable to stereotype threat than results from the prior 2019-20 and 2020-21 cohorts. Similar to the recent findings from a national study of a growth mindset intervention, which teaches middle-school students that intelligence is malleable and that intellectual ability can be developed (Yeager et al., 2019), our results suggest that subtle yet precise psychological interventions can improve student outcomes at scale. This work contributes to a growing body of evidence suggesting powerful ways to improve academic success and advance equity through social--psychological interventions (Walton et al., 2018; Yeager & Walton, 2011), which change how adolescents think or feel about themselves and their schoolwork and thereby open new avenues through which students can thrive academically.