I think your only option is to move out until she's out of the house (skids don't magically disappear at 18 though).  Seems as though your DH just has his head in the sand and won't do anything about this. Maybe she will get caught stealing from stores and then get charges pressed, and your DH won't be able to do anything for her.  He's doing her a disservice by rescuing her from any consequences, but parents like him think they are helping, not hurting. Is she even in any therapy?

Though I'd have trouble wanting to stay married to a man who would rather I move out than deal with his child's behavior.

I don't think I could live with someone as irresponsible as your husband -- I mean, putting a kid like that out into the world without even trying to straighten her out is so...unattractive. It's like marrying a man who doesn't pay his taxes or parks in handicap spots -- it's just sort of ugly.

In this case, though, you are also a victim if she's stealing from you, so do you want to be a victim? Do you want to be a door mat? Are you willing to sit back and watch this escalate until she takes your car and wrecks it, empties your bank account, or ends up the lead story in your local newspaper?

I think your only way of protecting yourself is to move out because stealing will become bigger problems -- it's a sign of something wrong. If not addressed, whatever is wrong will take over this girl. You might end up with a junkie in your house, a few babies, maybe some baby's daddies... At this point, you want this girl to be moving on, but he's giving her all the tools to become stuck in your basement. Maybe if you protest by leaving now, it will be the wakeup call he needs. I doubt it, but at least you'll be at a distance from the drama.

And I think it might be really fun to get your own place! Imagine that...when was the last time you got to live alone and do what you want when you want????? It could be good for you on sooooo many levels!

If your DH gets annoyed with YOU that you've found stuff in his daughter's bedroom, then you really have a DH issue.  Until he decides to be a real parent, nothing will stop your SD from doing this.

You can't stop her from stealing, especially since your H is not actively doing anything about it. I'd consider moving out. Maybe this is the kick in the pants he needs to see that you are serious and tired of all the BS. Action speaks louder than words!

Sounds harsh but don't let her in your home. If she can't respect her father's house enough to not steal from him when she's old enough to know better, then she shouldn't be 'rewarded' with coming over (that's if she doesn't already live there). That will hopefully be the kick up the arse she needs to learn to be more respectful of others.