Understanding the extent to which caregivers perceive active shooter lockdown drills in K-12 schools as physically and emotionally safe for their children is pertinent, yet little empirical evidence exists. Negative parental perceptions of drills can lead to decreased student participation and compliance and amplify public concerns associated with school safety. This article introduces the Lockdown Impact Scale for Caregivers (LIS-C), a novel instrument developed to assess caregiver perceptions of K-12 school lockdown drills. Utilizing a national sample of 999 caregivers, this study validates the LIS-C through exploratory and confirmatory factor analyses, revealing a three-dimensional construct that includes perceived impact, school safety, and expressed concern. The development and validation of the LIS-C provide school-based mental health professionals with a psychometrically sound tool to address caregiver concerns, paving the way for a more informed and intentional implementation of lockdown drills. This research underscores the pertinence of examining caregiver perceptions to foster a safer and more supportive school environment.