Who is paying for this apartment? I'm a firm believer in not picking up the tab for our difficult children. They never learn that way. If you're footing the bill, she's not independent and you have every right to tell her what to do. In fact, I hope she has a job and is at least paying half the rent. If SHE is paying the rent, she can do what she wants to do. I just wouldn't let her move back with you if she gets evicted. Yes, if her friends smoke pot, she probably does too, if not worse. We learned the hard way. And, yes, the parents are the last to know because we don't want to believe it. Also, I'm learning fast that "I just use pot" is often, if not usually, a big fat lie. in my opinion the other mom has every right to set her difficult child up in any apartment she likes. If your daughter is going to find the losers, she'll find them with or without this young adult in her complex. There is no shortage of loser young adults who get into trouble and take drugs. It's in my opinion none of your business where this other young lady lives. You can't shield your daughter. She has to decide to make better choices in her friends. Good luck.