make it available to the nation as it sought to deal with this important, urgent problem.

There is almost nothing in this report that meets the usual scientific standard of 95 percent confidence that a statement is true. But there is much that is likely to be true (more probable than not), and some of these things are not obvious. There are also some findings that upset some conventional assumptions about the phenomenon we studied, and there are some pretty clear ideas about where the priorities for future research may lie that could strengthen the science base for understanding and preventing particular kinds of lethal school violence.

The report is organized in the following way. Part I presents the cases. They are preceeded by a short analytic section that explains why they were chosen, lays out the template used to collect the information, describes the sources consulted to obtain the information, and describes the procedures followed by the case authors and the committee for the protection of human subjects. Part I also presents a cross-case analysis of the similarities and differences among the specific cases to develop some plausible hypotheses about the causes, consequences, and effective methods of preventing and controlling these incidents.

Part II puts the cases into the context of the literature reviewed and uses the cross-case analysis to develop some observations about policy implications and research recommendations. In reading Part II, it is important to keep in mind that the work contained therein reflects sources beyond the cases. It presents statistics about trends in violence and findings from the literatures that seemed relevant to the inquiry.

We begin with the cases because, even though these are not all that we relied on, they are in many ways the heart of our understanding and the source of some of our most important ideas. It is valuable for readers to enter this field as we did—in an inductive, exploratory way rather than a deductive, hypothesis-confirming way. The cases, presented here as signed, stand-alone pieces by the case investigators, are full of surprising facts, poignant moments, and rich insights. They put a human face on the tragedies that have beset the nation. They fill in the gaps that empirical studies cannot address. Those who are more inclined toward a deductive approach and would like to see what observations we have drawn first and then to test them against the evidence of the cases should feel free to start with Part II and read the cases afterward.



Epidemic means an elevated level; it does not necessarily imply a contagious phenomenon. There could be a contagious mechanism at work, but that requires investigation.


One case in Portland, Oregon, involved a knife, and an international case involved arson.

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