Controlling gun crime continues to be a difficult challenge for policymakers and practitioners in the United States. In 2009, there were roughly 11,000 murders with firearms in the United State and another 326,000 non-fatal violent crimes with guns . The prevalence of guns is thought to contribute to particularly high levels of homicide in the United States, where some estimates imply that the total costs of gun violence -- including medical, criminal justice, and other costs -- could be well over $100 billion per year. Yet finding common ground for legislative solutions to this problem is quite difficult, making it especially critical to effectively enforce existing laws and utilize other prevention approaches. Indeed, debates on controlling firearms violence often revolve around whether the nation needs tougher gun laws or better enforcement of laws that already exist. However, these debates are not well informed by systematic information on what law enforcement agencies are doing to reduce gun violence, the success of those efforts, and the factors that facilitate or hinder those efforts. In order to inform debate on these issues and to highlight successful enforcement and prevention strategies to reduce gun violence, the Police Executive Research Forum (PERF) undertook a national study of gun violence prevention efforts by local police in urban jurisdictions. The study's objectives were to: 1) to describe the range, scope, and prevalence of police efforts to reduce gun violence; 2) to assess which practices are most effective, both generally and in combination with different gun laws; and 3) to determine how these efforts can be improved.