The events of April 20, 1999, at Columbine High School in Littleton, Colorado, uniquely changed American adolescence in ways that we are only now beginning to recognize. When Eric Harris and Dylan Klebold attacked their school that day with guns and bombs, they did more than kill 15 people, including themselves. They did more than wound students and devastate their families and their community. They changed the way adolescents and adults look at each other.

As America approaches the second anniversary of this terrible event we see some important lessons being learned-and forgotten. Ten are particularly important.

Lesson #1: The constellation of risk factors that lead to lethal youth violence is spreading to more and more youth. While the rate of youth homicide has dipped since the mid 1990s, this decrease is principally among poor minority youth living in the most violent neighborhoods, and tends to obscure the rise of the "school shooter" among middle class, white youth.

Lesson #2: There is emerging a sub-culture of adolescent terrorism to which alienated and troubled youth are drawn. Dylan and Eric set out to become cultural icons for angry, disaffected youth who sought revenge against the nastiness of exclusionary youth culture. Recent events suggest they succeeded in that. A look at the web page of a teenage boy in California who was apprehended just days before he implemented his plan to blow up his school confirms this.

Lesson #3: The toxic elements of popular culture - violent television, vicious videos, degrading music, and violence-desensitizing video games-are on the ascendancy. With the proportion of kids troubled enough to need professional mental health services doubling from 10% in the early 1970s to 20% today, there is no shortage of kids vulnerable to this poisonous culture. Add to this the availability of weapons, and it is a lethal combination. The average teenager reports that he could get a gun if he needed one, and with about half the households in the country harboring a gun there is little reason to doubt what kids say on this score.

Lesson #4: Most school shootings are thwarted or intercepted because other kids share information with adults. Most kids who kill "leak" their intent to other kids-and sometimes even to adults. We are making progress in convincing the peers of violent youth that they must take responsibility of recognizing this "leakage" and reporting it to caring and capable adults. In this we are seeking to replicate the success of the campaign to convince youth that "good friends don't let friends drive drunk."

Lesson #5: Many teenagers have secret lives of which even loving, capable parents are unaware. Dylan Kelbold effectively hid his homicidal plans from his parents, and in this was only an extreme case of a general pattern.. Bad things really do happen to good parents. Troubled kids often have secret lives in which they accumulate and suffer from victimization by peers and feelings of rejection and sadness, and the hoard their fantasies of revenge until the play it out as a violent scenario. Teenagers identify the ability to "take it" as a prime requisite for handling today's high school. The too- sensitive can't manage it.

Lesson # 6: Our culture supports several myths about adolescents that aggravate and contribute to hostile school environments. These myths include: "Boys will be boys," "There will always be bullies," and "There isn't much you can really do about sexual harassment." These beliefs inadvertently permit disrespectful behaviors to continue in our schools. Eric Harris and Dylan Klebold cited the constant tormenting and bullying they experienced by their peers as the reason for their violent retaliation. Disrespectful interactions do not have to be the ordinary course of events at school and need to be systematically addressed by adults and students. Preventing serious violence and retaliatory actions begins with intervention in its predecessor, the widespread "minor" emotional violence to which teenagers are exposed.

Lesson # 7: We need to listen to our kids. If a couple of students are expressing concerns for safety at school, it is very likely that they represent the feelings of others. Further, when students express anger towards classmates, they may be at risk for harming themselves or others. We are beginning to take this seriously, but too slowly. We still want to believe that "it isn't going to happen here," so we fail to take kids seriously. This was unfortunately the case at both Littleton High and Santana High schools.

Lesson # 8: Teachers, staff, administrators, and parents need to make certain adolescents know that they are genuinely cared about as people. Students consistently cite caring teachers as a major factor in their perceptions of safe schools. Caring teachers and other adults intervene in fights and other instances of bullying at school. They don't just walk by or watch. "School shooters" often feel that they have to take matters into their own hands, that they cannot count on the adults on campus to look out for their well-being. From Columbine, we learn that in failing to stop bullying we run the risk of extreme violence and retaliation.

Lesson #9: While the typical adolescent talks a lot about breaking away from families and adult supervision, when given a chance in private, many students report that schools need to be more closely monitored and supervised by adults in order to be safe places. Adolescents need and are requesting greater supervision than we have previously considered. As one young man put it, "We aren't mature enough to do it ourselves."

Lesson # 10: Surveillance equipment and metal detectors do not necessarily promote a sense of safety at school for students. Students say surveillance cameras help to identify the perpetrators after the fact. They report that metal detectors encourage some students to bring weapons to school to see if they can get away with it. Neither are adequate school safety strategies and neither address the underlying causes and contributors to violence on campus.

We need to listen to kids for answers to violence reduction and improving school safety. They are the ones in the environment all day. They are the ones experiencing the problems. Many students feel rejected and angry. Without listening to the spoken words, essays, or videotapes of our students, we are forced to listen, finally, when they act out. From building design to changing the schedules of seniors and freshmen to monitoring hallways, adolescents have many original and creative ideas which, if implemented, could promote a safer and more caring school environment. We cannot afford to ignore their input on a national problem that continues to reoccur. Wise administrators are listening to students from all sub-groups and cliques in their schools for help in reducing the potential of another school calamity.

As we approach the second anniversary of the deaths and injuries in Littleton, Colorado, we do so with the repetitive reminders that come to us via the news with increasing frequency-plots foiled or executed by boys (and even girls) who cannot make it through American adolescence without detouring to the dark side of our culture and going to war against the world in which they feel so aggrieved, rejected, humiliated, and alienated. Compassion and intelligence are needed to make sense of all this and to reach out to our youth in a caring way to keep them safe, all of them.

James Garbarino, PhD is Co-Director of the Family Life Development Center and Elizabeth Lee Vincent Professor of Human Development at Cornell University and author of Lost Boys: Why Our Sons Turn Violent and How We Can Save Them (NY:The Free Press, 1999).

Ellen deLara, PhD is a family therapist and post-doctoral fellow at the Family Life Development Center whose doctoral dissertation dealt with "Adolescents' Perceptions of Safety at School and Their Solutions for Enhancing Safety and Reducing School Violence."