J.C.
K., unlike some of the previous posts, I don't believe that your step daughter needs a therapist. At least not yet. In my home I have 2 step sons (now 18 & 13) and 2 daughters (now 8 & 10). My youngest daughter went through a phase where she was taking things too. Of course we sat down with her and talked to her at first. We thought that was the end of it, but it wasn't. But when something came into question again and her dad was seriously pissed off, I told her that she could come clean to me without me yelling at her. I just kept reminding her of this. Eventually she came clean and true to my word, I did not yell. But I did make her return the object (which was highly embarrassing) and apologize. She had this happen twice where I had her return the object. I suggest that you think about giving her an "out" where she won't get yelled at. Then follow through with whatever consequence you think is fit. Talk to her about how she would feel if someone took something of hers and about getting positive attention. After her "punishment/consequence" make sure to praise her if she takes/does it without much or any complaint. Praise her for doing the right thing and taking responsibility. I know this might sound silly, but I have found that positive reinforcement after a punishment really does work. It shows the kids that you know they didn't like it, but that you know they "took their medicine", so to speak. That you are proud of them for behaving the right way. Good luck. And if this behavior persists, then you may have to look for professional help, but I feel that to do that too soon can add to the problem. She might feel then that she is in control of the situation and getting you to do what she wants instead of the other way around. Or she might feel cornered. My younger step son went though a spell like this and his mother put him in therapy. He was kind of "fed" by the therapist and learned to work us all. Claiming that he didn't get enough attention, that he felt as though we all were ganging up on him. Personally I think this was all bullpoop. When I had him start writing tasks ("I will not take things that are not mine" -100 X's) etc., he finally started to respond. When he had things of his "stolen", he started to learn how it felt. When he had to return and apologize that is when he finally woke up. Taking the time (even though it didn't seem too important at the time) to praise him -and I mean really well, was the start to the complete turn around. He learned that by doing the right thing he got better results from all of us. Even offereing something that he really wanted to do (go to the skatepark on saturday for 2 hours) as a reward worked well. So, as you can see, this did work for my family. I hope that I have helped you at least a little. She is definately looking for attention, but you have to turn it into the right kind. Maybe some one-on-one time with Dad as a reward. Food for thought.