Your 4-year-old daughter's friend bosses her around during dress-up, hogs all the toys, and then refuses to help clean up the mess she made.
What you're tempted to do: Put her in a time-out or send her home.
What you should do: Your house, your consequences. Right? Well, yes, but restrain yourself -- maybe your little guest is just having a bad day. Reiterate the rules ("In our house we take turns, and everyone cleans up her own mess"), then offer a reward ("When you're done cleaning up, we'll have cookies and lemonade"). If she still won't play nicely, you might try having the kids play separately for a while and see whether that helps. Steer clear of time-outs unless you've gotten the mom's permission to give one. Even then, save it for more egregious behavior, such as when a child is throwing toys or being defiant. If necessary, ask if she'd like you to call her mother to see whether she has any suggestions (the mere threat might change her tune). Be up-front about the problems at pickup: "We were having a little trouble with getting along and sharing today."
In most cases, a visiting child will want to win your approval. Christy Majors, of Waynesboro, Virginia, hosts playdates all the time for her kids, Tess, 6, and Max, 3. "When someone misbehaves, I talk to them at eye level and treat them with respect," she adds. "Kids know when they're being dealt with fairly, and they'll usually cooperate in return."