I've had a number of people ask me about how safe is Bonnaroo. This is a valid concern and I thought I'd address it. In general Bonnaroo is very safe. There is a professional mounted security force active around the clock at the site. The vast majority of people there are friendly and harmless.
Women thinking about going to 'roo solo have emailed me with concerns about being alone. There are so many people there no one is really ever "alone", if anyone ever has a problem with someone, hundreds (if not thousands), of people are a shout away.
The only safety related issues I've heard of is petty theft from people's tents when they are not at their campsite. Even that is really pretty rare, just don't have anything of great value out in the open (keep valuables on your person or locked in your car) and you should be fine.
Finally, I've had parents contact me wondering if they should let their teenage children go to 'roo. Ultimately that comes down to how much you trust your child's judgment and personal responsibility, as alcohol and drugs are rather easy to obtain at Bonnaroo. No one will "push" drugs on anyone, but they are available to anyone who looks for them. You are the best judge as to the maturity of your child and whether or not this is at all a concern. I've seen very mature 16 year olds at Bonnaroo, I've also seen people in their 40's passed out drunk at 11 am, so age isn't always a good metric.
Bonnaroo is a lot of fun and quite safe. In general, I think there are less "bad" people at Bonnaroo than in the general population. If you are smart you should be fine, just like anywhere else.