Guest Post by April M. Zeoli, PhD, MPH, and Shannon Frattaroli, PhD The phrase “mass shooting” calls to mind the recent and highly publicized tragedies of Newtown, Aurora, and Tucson. However, according to Mayors Against Illegal Guns, 40% of the mass shootings that occurred between January 2009 and January 2013 involved a perpetrator killing his current or former intimate partner and, often, her family members or children. Many of these perpetrators were known to the justice system because they had domestic violence charges against them or were the subjects of past restraining orders. Most victims of intimate partner homicide are not killed in mass shooting incidents. Instead, they are often their current or former intimate partners’ sole victims of lethal violence. Most intimate partner homicide victims are killed with firearms. Laws that keep firearms out of the hands of those with domestic violence restraining orders against them are an effective strategy for preventing intimate partner homicides. Other laws, such as restrictions on firearm possession for domestic violence misdemeanants, may also prevent homicide when properly implemented. In fact, implementation of these laws is both necessary to their success and often overlooked by state legislators, courts, and law enforcement. For example, while those under domestic violence restraining orders may be barred from possessing firearms under state law, ensuring restrained individuals relinquish their firearms is often not a systematic practice. However, in 2013, some state legislatures attended to implementation considerations for existing domestic violence firearm laws. Colorado and Connecticut now specify that respondents to restraining orders who are already prohibited from firearm possession must surrender their firearms. With better implementation of firearm policy, there is a potential to see a greater decrease in intimate partner homicide. This decrease in homicide may extend not only to intimate partners, but to those family members, friends, and children who are also murdered during domestic violence-related mass shootings. April M. Zeoli, PhD, MPH, is an assistant professor in the School of Criminal Justice at Michigan State University. Shannon Frattaroli, PhD, is the associate director for outreach in the Center for Injury Research and Policy at the Johns Hopkins Bloomberg School of Public Health. They are both contributors to Updated Evidence and Policy Developments on Reducing Gun Violence in America, edited by Daniel W. Webster and Jon S. Vernick. This digital update to Reducing Gun Violence in America presents new evidence and developments in the effort to address the staggering toll of gun violence in the United States. In 2013—in the wake of the tragic shooting at Sandy Hook Elementary School—Johns Hopkins University Press published Reducing Gun Violence in America, a collection of essays written by the world’s leading experts on gun violence. Updated Evidence and Policy Developments on Reducing Gun Violence in America follows up on the state of American gun violence by analyzing new data, research, and policy developments one year after Sandy Hook.