There are so many settings to keep it private and no one can see her profile unless approved . She of course should have computer in a room where you can monitor it but all her friends probably have accts
I'd say let her get one but stay her friend. See the ways she talks to others and how she uses it. If you suspect anything fishy, ask him/her about it. If you really trust your child to make that step, let her.
I don't see the problem getting one, she can easily connect with friends and socialize when not at school. But like others say, monitor her activity once in a while and force her to add you as a friend.
If she uses your computer and you say no, Then go into the parental controls on the computer if so equipped and block out facebook If she has her own computer Then check it out and do the same as you would on your computer. Kids need to realize that laws are there for a reason and must be obeyed Some kids break laws/rules to be cool or "in with the in crowd" Definitely not worth it