Shooting events and threats of shootings have come to shape the educational environment of many schools across the United States in recent years. Between 2021 and 2022, the number of threats alone rose by 60 percent, and most of these threats were made anonymously on various social media platforms commonly used by youth. While the overwhelming majority of these threats are meant to be jokes or to create havoc across a school or district, the resources that schools and law enforcement partners must devote to investigating and tracking down the source of each threat are significant. The resulting lockouts, lockdowns, and school cancelations that schools are often forced to implement have a severe emotional toll on students, teachers, and school staff. Seeking to shed additional light on how K-12 schools in the United States are being targeted by social media-based threats, the authors of this report examine what schools are doing to investigate each threat's credibility, ensure the safety of their communities, and work with local and other partners in these areas. To this end, they conducted a literature review to identify existing practices for assessing and responding to such threats, analyzed over 1,000 news reports about threats from 2012 to 2022 to identify trends, and interviewed more than 60 K-12 stakeholders representing 17 school districts in 12 U.S. states about the challenges these threats pose and the decision-making processes and active steps they take to respond to them.