AbstractThe toll from gun violence in American K-12 schools has escalated over the past 20 years. School administrators face pressure to prepare for possible active shootings, and often do so through drills, which can range from general lockdowns to simulations, involving masked “shooters” and simulated gunfire, and many variations in between. However, the broad and lasting impact of these drills on the well-being of school communities is poorly understood. To that end, this article applies machine learning and interrupted time series analysis to 54 million social media posts, both pre- and post-drills in 114 schools spanning 33 states. Drill dates and locations were identified via a survey, then posts were captured by geo-location, school social media following, and/or school social media group membership. Results indicate that anxiety, stress, and depression increased by 39–42% following the drills, but this was accompanied by increases in civic engagement (10–106%). This research, paired with the lack of strong evidence that drills save lives, suggests that proactive school safety strategies may be both more effective, and less detrimental to mental health, than drills.