Adolescence is a sensitive period for brain development. Although hippocampal volume, critical for memory and emotion regulation, is shaped by genetic and cognitive factors, it remains vulnerable to chronic stress. Family stressors such as poverty have been linked to altered adolescent hippocampal development. Threat of eviction is a leading stressor for U.S. families, with almost 7% of renter households facing eviction each year. Between March 13, 2020 and August 15, 2021, temporary eviction bans during the COVD-19 pandemic eased eviction threat. Leveraging state-by-state differences in eviction ban duration, prior work showed that the bans reduced mental distress in adults at risk for eviction, but it is unknown whether the bans also affected adolescent hippocampal development. Using a quasi-experimental study design with a difference-in-differences estimator, we estimated the effect of eviction ban coverage on hippocampal development in the Adolescent Brain and Cognitive Development (ABCD) cohort (N = 11,718 from 21 sites across 17 states, baseline in 2016-2018 at age 9-10). Participants were categorized as a ‘long ban’ group (states with total eviction ban duration >450 days, range 470-518 days) and a ‘short ban’ group (<200 days, range 0-192 days). Hippocampal volume was assessed at 2-year intervals through 2024 (Freesurfer segmentation of T1-weighted magnetic resonance images). We used linear regression models with standard errors clustered at the subject level and adjusted for intracranial volume, age, site, state, and subject (which reduces demographic and socioeconomic confounding). Residing in a long ban state was associated with 44.1 mm3 (95% CI: 32.8, 55.4) greater bilateral hippocampal volume growth compared to the short ban group. Other COVID-era policies, including containment measures and economic support, were not associated with hippocampal volume change. Therefore, social safety net policies may support adolescent brain development.