I realize I am a little late in posting to this thread, but it was bumped up so I thought I would add my 2 cents. When people live with you, in your home, you are the one who gets to make the rules...whether these people are your children or others. It is never unreasonable to a) want to know where your child is, no matter their age; b) expect that the person who lives under your roof will respect the curfew you have set for your home and c) remind this person from time to time that when they are the one paying the bills, they will get to make the decisions/rules...until that time it is your domain and your rules.

My kids had curfews, so long as they lived under my roof...didn't matter if they were in high school or 25. Our 32 year old son, knows that if he ever needs to move back in for any reason we still have the same rules we have always had...which means we know where he is, who he is with and when to expect him home...now obviously if he isn't coming home that night we'd know that too ahead of time...and if he said he'd be home, then didn't show up he'd get his ear chewed when I saw him.

We didn't have a curfew written in stone...the curfew depended upon the activity and maturity of the child in question. Generally though if they were in high school midnight was it for Friday & Saturday night, 10 weeknights during the Summer and 9 during the school year (unless they were attending a school event, then they had to come directly home when it was over). Once they were out of school it was still 10 weeknights since their dad worked and 2a.m. on weekends...