Your concern is understandable. As a profession it is short and unstable. However many other professions have similar problems.
The promise of a life of glamour is very tempting but at the same time it is a fake one. So it is usually very dissapointing.

This is what wikipedia says about their working conditions:
Despite the stereotype of modeling as a lucrative and glamorous profession, according to the US Bureau of Labor Statistics the median wage for models was only $11.22 per hour in 2006.7 MarketWatch listed modeling as one of the ten worst jobs in America.7
(this MarketWatch article is from November 2007).

However, if she has a genuine interest in arts and fashion or even acting, I say encourage her. This will give you the possibility to protect her because she will need you eventually.
What kind of support could it be?

First of all talk about it
- What aspects of modeling she likes? Some models are theatrical and act out for their work, some become actresses.
- What are her expectations? Does she want to be a diva, a muse or a real professional?
- Does she have any other interest? Design, photography, writing!

Second, research together
- Talk to professional models or read biographies.
- Talk to former models (this is a key issue and more interesting biographies)
- Talk to photographers, fashion designers, fashion editors
This talks would be useful to understand how the industry works, what are they looking for and to broaden the options for her role in the industry.

Gather all this information and you will find the answer together, maybe she realizes it is not what she expected or maybe you will become her number one fan.

As with everything, when raising children, care and concer is the angle.

Ultimately, they will do whatever they want. It's the nature of the beast. However, you can arm them and give them what they need to make informed decisions.

Explaijn the pros and cons. Some are:

Pros: fame, money, influence, free stuff

Cons: objectification, ulterior motives, pressure to conform.

The scariest thing for me is the pressure. I hope you can (or have) instill in your daughter a healthy self image. Unfortunately, the modeling industry encourages very thin bodies, and models have historically had a higher incidence of eating disorders. Also, drug use can be a problem too. Caution her in these areas.

Remember, the choice is hers, but you are the most important source of information she'll ever have.

(I'll add references later: I'm doing this from my phone in Opera Mini)

I think you should encourage her, maybe not necessarily in modeling but in fighting for what she wants in life. She may or may not stick with the idea of wanting to model (the younger they are the more they tend to change their mind) but you will want to encourage morals that you believe in. Ex: staying in school, modesty etc. So no matter what she chooses to do (because ultimately it will be her decision no matter what you encourage her to do) at least she will have some guidelines that will help her make decisions. I hope this helps!

I'll agree with the encouragement... but with this kind of job, there needs to be a LOT of communication - both ways.

She needs to understand what it takes to be a model and the consequences of being a model.

As a parent, I'd be talking to her about the attitudes and thoughts around eating (and what constitutes an eating disorder) and self-esteem.

There probably needs to be a bunch of self-reflection on BOTH of your parts. It's VERY easy to get drawn into the illusion and think this is how reality is... very similar to sports and movies/TV. You can make a bunch of money and people treat you different than how people treat you in "real life". Healthy people keep themselves grounded and reality-based.

Parents should encourage any dreams their children have, within reason of course.

I think it is our responsibility to encourage our children to dream and go for that dream.

My son wants to be a rapper/singer and I have encouraged him from day one to do it. Even though I encourage him to sing, write songs and perform when he can, I also made sure he got an education and a job (when he was old enough) to support himself until he made it as a rapper.

Let her try to be a model you never know, she could be the next big thing!

This is one of the few areas that sends up red flags for me. Mostly I'm a huge believer that parents should help kids follow their dreams, instead of dictating their dreams or squelching them.

But this is one area where if you win, you stand a big chance of losing; and if you lose, you lose.

If you win, there is the risk of eating disorders; tabloid lies; invasion of privacy; and being taken advantage of by handlers. With terrific support it may be possible to dodge all these bullets.

If you loose, there's still the chance that any or all of these things will have happened to you.

The one person I know well who was a runway model for awhile on a world scale (Paris, Milan, London shows) quit when her photographer told her that in order for him to get the best shots, he'd have to "get to know her better", by which he meant sleep with him. She was 15 years old, and he was in his 30's. Her parents had sacrificed a lot for her career and she was scared to death to not do as he said, but she reported him anyhow. That ended her career. No one would touch her. Her career as a model was over, but she went on to college and eventually became a lawyer. Now she prosecutes guys like him.

Maybe your daughter could somehow avoid all the pitfalls. Maybe some people do.