Your daughter definitely needs some guidance but because she is in a bad cycle right now, you can't give it to her just yet. First take a few weeks to build up a positive cycle. Don't criticize her or show anger at all; don't threaten or punish right now. Use praise, gifts, hugs, jokes, sympathy, empathy and lots of other kinds of positive attention. If she is really negative with you, just ignore it for now (unless she's doing something dangerous, of course). Once you've solidified your positive stance, you can begin to set a very few limits. If she says hurtful things to you, let her know that she's hurting you. Let her know that it's not an O.K. way to express herself. Show her a better way and tell her that if she does it again, there will have to be a negative consequence - then stick to that. Don't excuse her bad behavior because she is insecure, unsettled or otherwise emotionally fragile. After a week or two, you can address her unacceptable behavior with her siblings in the same way - explaining the damage, setting a limit, threatening a consequence and carrying through if necessary (see "Raise Your Kids without Raising Your Voice" for ideas for consequences for teens). As long as you continue to be mostly positive (90% positive) you can afford to be very strict on the few unacceptable/hurtful behaviors she is engaging in - particularly, the hurtful words. With this firm but loving approach, she will eventually heal from whatever is bothering her and her behavior should improve. If, after applying this program for a couple of months, you don't see results, get professional help for yourself and your daughter.    Sarah Chana