when nothing can be done ...

I will take action IF the kid runs away. I have major doubts ; For now I can't call the mom (or the school) and say look, your daughter told my daughter that she thinks maybe she plans to run away ... especially if there's abuse there, I would hate to think the consequences this would have on the child.
Quoting Anonymous 5: Have you thought about how you will handle it if the child does run away and is injured or harmed or even if the child kills herself. Your lack of action is unacceptable. Call the school and tell someone with authority. You don't need to give your name.

no that's not the case ... I know from experience.
I'm just saying, I now certain circunstances about that kid where I know parents who don't care about their child, would not do, in this case she is clearly well cared for. And I know abuse comes into may forms; the kids biggest complain is that her dad screams a lot and her mom doesn't care about her problems. I can tell you that I went through the same thing as a teenager, my dad had a really bad temper and my mom couldn't give a shit about what I was going through as a teenager, we didn't get along, my mom by far was more attentionate towards my sister than she was to me, I was the black sheep. I used to spend all my weekends at my friend's house, my mom wouldn't call once to see if I was really there or still alive. It's still a taboo subject today my mom refuses to admit to that and she'll say that she was the poor abused lamb and that I was an evil chiild, But llooking back It doesn't mean my parents were abusive. KWIM?
Quoting Anonymous 6: I hope you don’t think abusers can’t have good careers Bc that is what it sounds like .

I would call the school and talk to the school principal. They are mandated reporters so if there is abuse going on in the home, they'll report it to CPS. How old are these girls?

Or you teach your child that there are times that they need to do the right thing if they care about someone even if it means that person might be upset with them. You also teach your child how to use their resources and advocate for themselves and those they care for.
Going to a school counselor (who is a mandatory reporter) is the best option.
Quoting AmaliaD: As the mom of a 12 year old- that trusts me. I’d do nothing. I’d tell no one. I’d maintain the trust. I would not expect the kid to really run away. We would talk about what happened when stuff happens. But sometimes you just need to do nothing and that’s the worst.

I have seen what suicide does to families. I could not forgive myself if I could have prevented that.
DD knows that life is more important than friendship.
Quoting Anonymous 5: Have you thought about how you will handle it if the child does run away and is injured or harmed or even if the child kills herself.
Your lack of action is unacceptable.
Call the school and tell someone with authority. You don't need to give your name.

As the parent of a son who was going through depression, self harm and contemplated suicide, PLEASE let someone at the school know what's going on. I also attempted suicide when I was a teen and I missed all the signs my son was giving. My son and I both come from loving families, although I grew up with an alcoholic father which is what caused some of my depression.
Just because you think you know how the things are in that family doesn't mean anything as to what that child might be going through. Please don't just do nothing. She may be being just dramatic, but this is one of those situations where you should act on the "what ifs".

the girl in question is 15
I very highly doubt there's abuse in the home - call it a gutt feeling. I will bet my next pay check that the girl is in school today and did not run away last night as she had confided in my DD. I will wait until my daughter comes home from work to find out. If the girl did run away - I will call the mom and the school
A friend of mine went through living hell when someone from her daughter's school got CPS involved because they thought maybe something was off - so not putting someone through this over a teenager's tantrum
Quoting PinkButterfly66:I would call the school and talk to the school principal. They are mandated reporters so if there is abuse going on in the home, they'll report it to CPS. How old are these girls?
Your lack of action is unacceptable.
Call the school and tell someone with authority. You don't need to give your name.