How would you handle this?

well, i doubt you can do much at all when she's at school. but at 13, you can always monitor her whereabouts outside of school...by not allowing her to be where these girls are.
she doesn't have to have a phone or texting priviledges, either. they aren't necessary to a 13yo's life.

During the school day you probably can't. Outside of school be vigilant about where she goes and what she is doing. Let her know that you will be checking up on her and there will be consequences if she is found to be with those girls. I have no way of know if any of these would work at all or only cause resentment. Good luck in whatever approach you find that works for the both of you.

I would wonder why she is attracted to this group, and your her parent, so if you don't want her to hang out, go over with them outside of school, lay down the law,, I find it hard to believe that EVERY girl in this group has prison, druggie parents,, have you talked to her about why she feels comfortable in this group,, and honestly if it go to where her grades, activities and things were failing I migh switch her school. WHO informed you of the bad girls club reputation? I might be prone to investigate it more, rather than taking someone else's word for it.

At school you cant. Keep her busy in healthy activities like softball, volleyball, or whatever is popular in your region. I found keeping my teens busy gave them less of a chance to choose bad friends. They all stayed within the circle they played sports with since they see them after school and on weekends too.
You can also contact the school and inform them you dont like her being around those kids and ask what options you have. Can you change her out of classes they share? Then get a hold of the parents and nicely tell them you do not want your child hanging around with their child because together they get into trouble. That way you arent finger pointing.

I agree with meooma. I would closely monitor her activities outside of school. You can track her on her cell phone with that gps plan to be sure she is at designated locations. I would demand to randomly go through her phone and facebook messages. Check the phonebill to see who she might be deleting messages from on the phone. Maintain contact with teachers to know if she is skipping class with these girls. Get her involved with an outside activity where she will make new friends . The privacy and trust is over when a teen breaks the rules, and its up to us as parents to set the boundaries. GL!

well then step in and say she isn't allow to see them outside of school, and perhaps find an activity for her that she will be involved with other girls who have more like minded parents,, and if I saw teens posting like that to an adult, and he was responding, I think he should have been reported.

Enroll her in extracurricular activities. Sports, Volunteering at the Library, After School activity. What are her interests? Ask her & pursue them. Keep her too busy to socialize with these girls. I would also speak to the Principal of the school so they can be aware of possible problems with these girls. Take away her Facebook privilege. It is a waste of time when she could be doing something productive. Busy hands are happy hands!

I think there are things you can do to discourage these friendships without outright forbidding them, which might just make her more drawn to these girls if rebellion is a part of the draw they have for her. As Ilovemypaulie suggests, keep her engaged in activities that build upon her strengths and interests. I would certainly not let her go over to these girls houses or go hang out with them unsupervised, but if they come over to your house, you can supervise them and you and your family could be a positive role model for them.

Keep her really busy with other activities