I think you just answered your own question.You are the parent and she is the child.
1)You say you ground her - and never make it stick, well make it stick.
2)You say you are too easy on her - then get tough.
3) You know it is wrong - so only you can change what you know is wrong

Set the rules and consequences and stick with it, when you need support start a discussion and everyone here will give you support to know end. You need to be the parent and let your child know she is not in charge.

I, too, have trouble "making it stick" and I can say from experience that smcollins is absolutely right! You have to be her "parent." She has plenty of "friends." What we did with my son was enforce a "natural and logical consequences" plan (anyone else out there tried Love and Logic?). If he fails classes due to not doing the work, then he has to be home during the week because he obviously needs more time to get his work done. (If he fails because he "didn't get it" then we work with him on it, however this is rare.) If he has to do summer school, he has to pay for it out of his own pocket. One thing that did work for us was giving him something to work for (he really wanted to be able to do what he wanted with his own hair over the summer, so the deal was, pass everything and don't make us ride his butt about it all the time and he could do what he wanted with his hair. It drives grandparents nuts, but he's going to the next grade with all of his credits, which didn't happen last year, and hopefully learning that there are rewards for working hard.) Good luck!

All through middle school I got really bad grades. I am smart and I was smart I knew I could do it but I would try and it just wouldn't do much good. I would have loved for my mom or dad to say everyday "Veronica do you have homework?" then I would have done it and I would have been better. It's usually the homework thats gets people. and yeah I'm 14 I'm not a parent and whatever but I think I might be able to help. My mom would ground me and it wouldn't do much for me, because there was always ok it's going to be so and so days and it's going to be over. I really don't think groundings are a good punishment inless you are making her earn stuff. Lets say she wants to go to a friends house first she needs to earn that. Sorry if this doesn't help. I'm just trying.

i have a 15 yr old step daughter plus a 13yr old girl and 3 boys, 11 with adhd,9,and 7. my husbands ex wife is now living with his brother the kids uncle, so having to deal with that then me and there mom dont get on, and the kids are starved of antention, you have to give children structure they need and want disapline guild lines and for you to be consistent even when punishing them. so stick to your guns. xx tara xx

I agree with hopefulmom, the love and logical consequence approach is rather new to me. I've been reading the book Positive Discipline by Jane Nelsen, Ed.D. and it has helped to open my eyes as to why things are so different with children of today as opposed to when I grew up and when my parents grew up. I've used the love and logic approach this past weekend with my 6 year old with something as simple as eating meals with the family. If she didn't want it or didn't finish it all she got nothing until the next meal. She quickly learned that she should clean her plate because she won't be getting the good treats between meals or desserts when others in the family did get them.