Background: Students' social emotional competencies (SECs; also known as non-cognitive skills) are the skills or knowledge that allow them to successfully navigate social and academic environments such as self-management, social awareness, and relationship skills. Research has established cross-sectional associations between SECs and student outcomes (Farrington et al., 2012). Fewer studies have examined these associations longitudinally, including with econometric fixed effects methods to address unmeasured confounders. This study fills that gap. Purpose: We examine five SEC domains defined by CASEL: self-awareness, self-management, social awareness, relationship skills, and responsible decision-making. We further divided these domains into 8 subdomains including self-management in the areas of emotions, goals, and schoolwork. Based on a small, but growing body of research (Claro & Loeb, 2019; Gordon et al., 2022), we anticipate that self-management of schoolwork will be associated with GPA. A major contribution of our study is testing these relationships in an adolescent sample. There are fewer studies on SECs and academic outcomes in high school samples compared to early childhood and elementary school (Cipriano et al., 2023). High school is relatively understudied, despite the increased academic and social demands during that period. We first describe changes in SECs and GPA between 9th and 11th grades and then examine the association between those changes. Research Questions: R1: Are SECs and GPA stable overtime? Or do they change for students from 9th to 11th grade? R2: Does a change SECs relate to a change in GPA in 9th and 11th grades? Setting: This study took place at a mid-sized urban school district in the Western United States. Participants: The study examined a longitudinal sample of high school students in the 2020 graduating cohort. We examined two time points, 9th and 11th grades (the high school years the climate survey was administered), and 4,652 students who were enrolled in school at both timepoints (see Table 1). Research Design: The current study used a quantitative secondary analysis survey design. District administrative data were linked to the annual school climate survey, where SEC data are collected. Data Collection and Analysis: Students completed the 40-item WCSD-SECA as part of the district's annual climate survey that is administered during the school day. The WCSD-SECA was designed using a rigorous mixed-method continuous measure improvement approach to align with the CASEL 5 (Davidson et al., 2018) but uses 8 subscales rather than 5, (see Table 2). Students rate how easy or difficult each of the items are for them on a 4-point scale from 1 = Very Difficult to 4 = Very Easy, and we calculated average scores for each domain. Students who answered at least one survey item for each domain were included in calculations. Sixty-one percent of students completed the survey in both 9th and 11th grades, 32% took the survey one year, and 7% never took the survey. We used multiple imputation to impute survey data for the 32% of the students who only took the survey one year. After imputing the data, we applied the first difference regression approach (Allison, 2009; Angrist & Pischke, 2009) to assess the longitudinal relationship between changes in SECs in 9th and 11th grade and GPA. Analogous to a two-panel fixed effects model, the approach uses difference scores (?) to account for time-invariant heterogeneity (Allison, 2009; Angrist & Pischke, 2009). We calculated the difference scores by subtracting 11th grade survey responses and GPA (t2) from their 9th grade survey responses and GPA (t1). Student identifiers are collected on the survey and were used to link to their school records. We used students' average Grade Point Average (GPA) on a scale of 0.0 to 4.0 as the outcome variable. We controlled for yearly academic risk, which is a composite score of risk indicators based on attendance, suspensions, and school changes in the current academic year and is predictive of GPA. Results: R1: Are GPA and SECs stable overtime? Descriptive analyses indicate that on average, GPA decreased by 0.17 points between 9th and 11th grades. Because of the large variability in the SEC differences scores (Figure 1), we examined how many students changed by half a standard deviation or more for each SEC (see Figure 2). The largest changes in the eight WCSD-SECA subscales were for self-management of schoolwork, with over a third of students (37%) reporting a decline between 9th and 11th grades and 27% reporting an increase. R2: Does a change in SECs relate to a change in GPA? To answer the second research question, we ran a first difference regression model to assess the association between change in SECs and change in GPA between 9th and 11th grade (see Table 3). Both changes in social awareness (B = -0.06, SE = 0.02, p < 0.05) and self-management of schoolwork (B = 0.11, SE = 0.02, p < 0.01) between 9th and 11th grades were associated with changes in GPA. In other words, students who reported gains in self-management of schoolwork also saw GPA gains, whereas students who reported gains in social awareness in 11th grade also experienced a decline in their GPA. Conclusion: In this study, we examined longitudinal relationships between SECs and academic outcomes in a high school sample. Consistent with past research that suggests learning strategies decline in adolescence (Bardach et al., 2023) our results show a decline in self-management of schoolwork in high school. An econometric first difference approach indicated that changes in self-management skills (as well as social awareness) are also associated with changes in GPA. The findings of this study have important implications for social emotional programming and policy. Using an econometric first difference approach, this study reveals the association between self-management skills and academic growth remains after washing away time constant effects of time constant confounders. Policies and programs that build students' self-management skills in adolescence are thus needed to better equip them to meet the increasing expectations and demands of high school. Future research should continue to examine these associations and associated programs and policies in other contexts, as this study took place in one school district.