School-wide attendance rates and firearm-involved expulsions in Michigan K-12 public schools, 2018-2022.

This ecological study estimated associations between school-wide attendance and expulsions for student firearm possession using administrative data for Michigan public K-12 schools from 2018-2022 (N=2,866 schools). Between the 2018-19 and 2021-22 school years, 77 Michigan public schools (2.7%) expelled students for firearm possession. In unadjusted models, higher rates of on-track attendance (i.e., the proportion of students who attend ≥90% of school days) were associated with lower odds of the school having an expulsion for student firearm possession (OR=0.96; 95% CI=0.95, 0.97). This association remained after adjusting for student body demographics, school building characteristics, and school rates of student interpersonal violence and discipline (aOR=0.97; 95% CI=0.95, 0.98). Efforts to improve school-wide attendance may offer a primary and universal prevention avenue against student firearm possession.