We alluded to this fact on the last page, but we'll be a little less subtle now. He may always be your little boy, but he's also a grown man now. He's got an adult's life -- and an adult's agenda.
Chances are he'll spend the night out every once in awhile, and though it's OK to ask him not to bring dates home for the night, you can't expect him to act like he's living in a monastery.
If your adult comes home with children in tow, let him set the ground rules for his kids. Try to avoid cross-parenting. He's got his own child-rearing style, and though you should definitely be a voice of authority, the buck ultimately has to stop with Mom and Dad, not Grandma or Grandpa -- regardless of who's paying the bills.
The truth is, when an adult child moves home, it's not an ideal situation for anyone. Even if you don't mind helping out, it's a huge inconvenience and financial burden, and shacking up with Mom and Dad isn't how your kid planned to spend the next few weeks, months or (gasp) years of his life, either. Therefore, everyone involved should respect one another's needs, boundaries and authority. If all else fails and no one's happy, look into alternative arrangements. Yes, we're talking about forcing your once-little bird out of the nest -- it won't be pleasant, but it's got to happen sometime.