Just as when decorating for adults, when decorating for kids, form should follow function first–then aesthetic taste. In other words the first step should always be to consider how the room will be used, not only in general terms, but in detail: What specific activities need to be accommodated in this particular space?

For example, babies' rooms, or nurseries, generally need to provide space and surfaces for sleep, changing, storage of clothes and small toys and maybe a rocking chair or cradle. Young kids' rooms can lose the changing table and maybe the rocking chair, but need space for play and arts and crafts, and once kids leave their toddler years they usually want to have a say in the decor.

And teens, in turn, have their own set of needs. Up until the last ten years or so, most people didn't think of teen decorating as separate from decorating for younger kids–as little Jane got older, everything in her room was left pretty much the same except for an abundance of posters and dirty clothes on the floor.

In recent years, though, as the market for home furnishings for non-adults has exploded, new ideas about what kids need in their rooms have emerged as well as new lines of furniture targeted specifically for them. The reigning trend dictates that teens fare best in sort of apartment-within-the-house, minus the kitchen but with a private bath. The idea is that this will help ease the eventual transition into independent living, while still keeping the family and teen within close reach of one another. And the private bath makes the long hours teens tend to spend there a little easier on the rest of the household.

So here's a rundown of the basic elements you'll want to include in a modern teen's room:

The Usual Suspects
 Regardless of whatever else the room will offer, the bed, work area and storage are still the essentials. A desk that is large enough to hold a computer and still have ample space to spread out papers and books is ideal, as is a comfortable, ergonomically sound chair. The good chair is more important than ever, as sitting at a desk e-mailing has come to rival talking on the phone as the favorite teen activity.

Storage is also more important now than when they were younger, as this is the age when kids really get into defining themselves by their stuff: clothes, makeup, sneakers, magazines, CDs, trendy electronic gadgets, and more clothes are of the utmost importance to your average teen. And while everyone knows that most teens are serious slobs, providing ample storage for the mass junk they'll accumulate can help keep the mess to whatever minimum of neatness they can manage.

And speaking of storage, don't forget to include extra storage options in the bathroom for the vast assortment of grooming products teens often like to experiment with, and that includes guys as well as girls. These days it's more than just Oxy-10 and hair gel-now there's a different paint-on haircolor for each day, body glitter, unisex nail polish, and more creams and potions and pomades aimed at the teen market than you can shake a stick at.

The Connection
  It goes without saying that teens like to talk on the phone at great length, so you might as well work it into the decorating scheme–and make sure that it's either cordless or on a very long cord that can move easily between the desk, the bed and the bathroom, or consider having more than one extension in the room. And bear in mind that it might be easier on the rest of the household if it's on a separate line from the rest of the house. As for the phone itself, there's a wide assortment of novelty phones on the market ranging from nifty to tacky and beyond. Clear plastic, in fruity iMac colors, is hot right now.

Come in, Sit Down, Relax
It has become common for teens to have not only a bed, but a sofa or pair of comfortable chairs–sort of a personal miniature living room for entertaining friends and watching TV. For many parents the jury is still out on this one, for it encourages kids to stay in their rooms all the time without ever interacting with the rest of the family. For others, though, it's all the better not to be subjected to teen taste in music and movies–after all, a little Britney can go a long way. And a sofa can double as an extra bed for friends sleeping over, another diehard teen favorite. An inexpensive, undersized, foam-rubber fold-out sofa might be a good idea, or even one of the newer inflatable ones (watch out for kitty with those, though–one sharp claw might be the end).

Sound and the Fury
 And speaking of Britney, most teens like to crank up the tunes as loud as you'll let them. It must be something hormonal–apparently they just can't hear the music unless the folks in the next town can hear it too. To save your own sanity if not your ears, you might want to include a lot of fabric and carpeting in the room to absorb some of the sound. Big pillows on the floor and clothes folded on shelves instead of in drawers are also good for this. It's probably not such a good idea to totally soundproof the place, however–it's good to be able to tell when they're home, and of course you want to be able to hear them call if something's wrong.

The Bottom Line
Above all, the main thing to remember when decorating for a teen is to do it with his or her input. At this age, kids are all about creating an environment that expresses who they are, and if you don't cater to this need then they will take the lovely and seemingly reasonable decorating scheme you devise without them and alter it beyond recognition. You might as well work with them, and you may find it comforting that teens are now more design-conscious than ever before. All the marketing the design industry is aiming at them is making its mark on their taste, and many teens now really care about what constitutes good design and want to surround themselves with it.

Good luck and have fun!