The current study examines failed mass shootings in the United States between 2003 and 2018. This exploratory research provides a summary of failed mass shooting perpetrator and incident characteristics, drawing from crime script analysis to examine the preparation, attack, and conclusion stages, as well as points of failure. Findings indicate suicidal ideation, attack realities, and weapon preparedness may play a role in attack failures. Furthermore, situational crime prevention (SCP) techniques including target hardening and access control contributed to harm mitigation when individuals without legitimate access conducted attacks. Internal SCP measures, including lockdowns, place managers, and armed security, helped prevent victimization in open access or semi-protected locations once the perpetrator entered the building. A discussion of findings highlights implications for public safety and policy.