BACKGROUND A 2011 nationwide school pandemic preparedness study found schools to be deficient. We examined the impact of a school nurse educational intervention aimed at improving K‐12 school biological event preparedness. METHODS Missouri Association of School Nurses (MASN) members were e‐mailed a survey link in fall 2013 (ie, preintervention), links to online education modules (ie, intervention) in late fall, and a postintervention survey link in spring, 2014. School biological event readiness was measured using 35 indicators, for a possible score range of 0‐35. A paired t‐test compared pre‐ to postintervention preparedness scores. RESULTS A total of 133 school nurses (33.6% response rate) completed a survey; 35.3% of those (N = 47) completed both pre‐ and postintervention survey that could be matched. Pre‐ and postintervention preparedness scores ranged from 5 to 28.5 (x‾ = 13.3) and 6.5 to 25 (x‾ = 14.8), respectively. Postintervention scores were significantly higher than preintervention scores for those who watched at least 1 module (t = −2.3, p < .05). CONCLUSION: The education intervention was effective at improving school preparedness, though the impact was small. The education intervention needs to be reassessed, especially in regard to providing a longer intervention period.