There is widespread agreement that many school shootings could be prevented if authorities were informed that a student was planning or preparing to carry out an attack. A universal problem is that young people are highly reluctant to report on their peers. This code of silence represents a major barrier to prevention efforts. In response to the Columbine shooting, the state of Colorado established the Safe2Tell[R] anonymous, 24/7 reporting system for receiving and forwarding threats of violence, bullying, and other concerns. This article describes how the program has grown to the point that it now receives more than 100 calls per month. A series of case examples illustrates its success in responding to threatening situations, including twenty-eight potential school attacks. (Contains 3 notes.)