Beginning in fall 2026, growth measures will be added to California’s school accountability dashboard. Yet an important question remains: How much of the observed academic growth reflects the inequality of opportunity rather than student effort, aptitude, and the work of educators? This study used hierarchical linear modeling and empirical Bayes estimation to examine the contributions of opportunity to the growth trajectories of elementary‑ and middle‑school cohorts across all California public schools from 2023 to 2025.Using Smarter Balanced Assessment (SBA) English language arts and math scores as achievement indicators, opportunity explained 32% of the variance in Grade 3 ELA scores and up to 8% of the variance in math growth through Grade 5. Compared to the elementary-school cohort, the middle-school cohort saw smaller effects with opportunity explaining 17% less variance in Grade 6 ELA achievement and 61% less of the variance in math growth through Grade 8. The reduced role of opportunity for the middle‑school cohort suggests that, over time, California schools may be mitigating the effects of structural inequality.
