What makes teenagers tick?
Minneapolis psychologist David Walsh, a former high school teacher and guidance counselor and the father of three children not far past their teens, wondered that very thing. Studying the most recent teenage brain science, Walsh found that contrary to recent beliefs, teens' brains undergo incredible growth and change, continuing the process of "blossoming and pruning" that started in infancy. The resulting unrest, he found, goes a long way to explaining teenagers' sometimes perplexing behavior.

Walsh, president of the National Institute on Media and the Family, a nonprofit group that researches the impact of media on children and families, reports his findings in his eighth book, "Why Do They Act That Way? A Survival Guide to the Adolescent Brain for You and Your Teen."

What sparked your interest in teenagers?
Like many parents, I found particular challenges, both as a psychologist and teacher, during the teenage years. I think I was particularly aware of many of the challenges that families face as kids become teenagers. ...

A journalist in New York told me, "One of the things that really struck me reading the book is you really like teenagers." I was glad that came through because I think we need to readjust our attitude about teenagers.

People tell kids that these are the best years of their lives. Is that true?
No, and I say that with some conviction. I have been doing [adult] workshops for the past three or four months based on the book. I start with that statement, which is "Enjoy these years; they're the best years in your life." Then I ask these adults, "How many of you now, from this vantage point, would agree with that?" I'd say overall certainly less than 10 percent, sometimes less than 5 percent. ... A lot of times, teenagers are as confused by what's going on inside as the people on the outside [are] trying to figure it out.

For example, for a 15-year-old boy to understand that there are days when all he can think about is sex does not mean he's some kind of weirdo or pervert. It means that's part of his normal development, and what you need to do is find ways to manage that in a responsible way.

How did your discoveries change your perspective on teenagers?
I found it exciting because of the implications; it's not that the science is interesting, [although] that's nice. But what I think is most important and the reason I wrote the book is the implications. ... For example, teenagers process communication in a different part of their brains than adults do. As luck would have it, they involve the anger center of their brains, so they frequently misinterpret things in the direction of anger and hostility.

Why is that helpful?
It helps me as a parent not take things so personally, to understand that our kids are not doing those things just to get to us or just to push our buttons, but it really has to do with their brain development.

What can parents do before their kids are teenagers to prepare for adolescence?
Understanding and knowing what to expect is a big help because then we're not as thrown by it. Then I think we're better able to keep our perspective and we're better able to execute some of the strategies and some of the skills we're going to need.

Having consistent, structured discipline, with clear expectations and consequences, and consistent enforcement becomes very important. Because even though the stakes [for younger kids] may not be as high, if you wait until the kids become teenagers and you try to go from kind of a laissez-faire to establish some kind of structure, it's much more difficult.

Are there any mistakes people make raising teens that can't be remedied?
I never say never. If we've made a mistake, we can always go back and try to repair whatever damage might be done, but we need to remember the more mistakes and the more serious the mistakes we make, the harder it is to repair the damage.

One mistake we make is granting kids the divorce they're asking for. ... Parenting is not an easy job, and during the teenage years we have to pay the price of some very uncomfortable moments. The payoff will come down the road, and that's what I talk about in the book, that parenthood is a delayed gratification activity. You're investing for the long term.

How can teens help each other?
Teenagers can support, and support in an honest and caring way, and that doesn't always mean saying what we think our friend's going to want to hear. .

Sometimes when our friends are in trouble, they don't need someone to just pat them on the back. They need someone to pat them on the back and say, "You know, there's a better way to do this." But going against peer pressure is very difficult.

What about sex?
I distinguish between talking with our kids about sex and talking with our kids about sexuality. Sex is about biology. It's how the body works, and it's the stuff of science. It's very, very, important that our kids know that, but sexuality is sex within a context of values, morality, responsibility, relationships and respect. It's a much richer conversation. Our kids are drenched in a media culture that teaches them about sex. Our kids need communication about sexuality and the only place they're going to get that is from their parents and teachers and people who care about them as total people.