We will never be able to profile the kind of person who becomes a mass shooter in our schools; they come from stable two-parent households like the Carneals and families that have been through divorce like the Lanzas. They are often very bright boys, but not always. So we cannot generalize or pinpoint young men who have all the necessary conditions when we don't really know what those conditions are. 

Prevention thus depends on encouraging kids to speak up when they hear rumors. And it depends, even more, on our willingness to commit resources to the mental health needs of our young. Finally, keeping guns, especially assault weapons, out of the hands of civilians is essential, overdue by decades.

Katherine S. Newman  is the Malcolm Forbes Class of 1941 Professor of Sociology and Public Affairs at Princeton. An earlier version of this article appeared in The Nation.

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