This study provides empirical benchmarks that quantify typical changes in students' reports of social and emotional skills in a large, diverse sample. Data come from six cohorts of students (N = 361,815; 6% Asian, 8% Black, 68% White, 75% Latinx, 50% Female) who responded to the CORE survey from 2015 to 2018 and help quantify typical gains/declines in growth mindset, self-efficacy, self-management, and social awareness. Results show fluctuations in skills between 4th and 12th grade (changes ranging from -0.33 to 0.23 standard deviations). Growth mindset increases in fourth grade, declines in fifth to seventh grade, then mostly increases. Self-efficacy, self-management, and social awareness decline in sixth to eighth grade. Self-management and social awareness, but not self-efficacy, show increases in 10th to 12th grade.