After the fatal shootings at Virginia Tech last April, colleges went shopping for hardware. They bought sirens, mass-messaging systems, surveillance cameras, and door locks. Some colleges armed their police departments for the first time. Others added assault rifles to their arsenals. "Active shooter" drills happened everywhere. As administrators responded to a new threat, however, they could not overlook one fact: Gadgets and guns might help colleges react to violence, but preventing it would require something else. Ultimately, prevention is all about communication. The importance of sharing information about troubled students was the crucial lesson of Virginia Tech. State and federal reports on the incident have urged colleges to create behavioral-threat-assessment teams to identify and help distressed students. But how should such teams function? Who should participate? What, exactly, is a "threat"? Those questions prevail as colleges confront the increasing complexity of student "wellness," the popular term for students' physical and mental health. In the 1990s, alcohol was the campus scourge. The next decade brought a new crisis: suicide, depression, and behavioral and emotional problems. The massacre at Virginia Tech entwined mental-health issues with campus safety and security as never before. It also broadened the expected roles that various people--in student affairs, residence life, campus security, and the faculty--should play in promoting students' welfare.