You can guess what I've got going on at my house tomorrow night.  A sleepover for a bunch of little girls. 

But, I'm not worried.  I've got it figured out.

How do you have a fun birthday party sleepover and not get all worked up by the whole thing?

1. Keep the number of guests manageable.  I would have loved to have more kids over, but I thought about how many can really stretch out on our small family room floor.  I want them to have fun and not get into squabbles, so I decided we would only invite a few.  The other girls that my daughter wanted to invite can come over individually for sleepovers at other times.
2. Don't overspend.  Yesterday I was tempted to buy lots of fun decorating things, a new shaped cake pan, take-home treat bags that I'd fill with all kinds of heavenly treats.  Then, my thrifty personality stepped in and told me to remember that they will still have plenty of fun without all that stuff.  And, all that stuff will cause me to have no fun.  So, I bought two sizes of fun paper plates and birthday candles. 
3. Give them the guidelines. If they've never been to your house before, lay down some simple rules for your giggling gaggle.  Remind them they are there to have fun, but it won't be fun if they break things or upset you. Keep it to just a few simple rules, so they're easy to remember.
4. If possible, get the fun started, then step away.  I couldn't do this when my kids were very small, but they're old enough now, that I can play more of a supervisory role.  I went to the library and got some Veggietale sing-along movies as an alternative to a birthday game that I would have to organize and prepare.  These girls love to sing and enjoy being silly, so if I pop the DVDs in the machine, I should be able to go put ear plugs in and enjoy a book upstairs.  They also plan to watch several Veggietale movies and eat popcorn - a perfect sleepover activity that doesn't cause anyone to lie awake (like scary movies do.)  I'll pull some of the board games out and put them in full view, so they have that option as well. 
5. Keep the food simple, too. The menu is pretty easy: frozen pizzas, purple cows, and birthday cake.  I like to decorate the birthday cake myself, so that is a little work.  I would buy a cake, if I didn't have the time or energy to do a cake. Purple Cows were popular last year. Those little girls can rip out some major belches after a big Purple Cow and a little personal coaching. To make a purple cow, put a scoop of vanilla ice cream into a tall glass. Pour in a generous amount of grape soda, then add mini marshmallows (I prefer white to the colored ones because the taste is different) and a straw.  Gulp and burp!
6. Check in once in awhile.  Sometimes disputes arise.  You do want to head that off, so pop in regularly and join a game or give someone a compliment on their cute pajamas. Watch the girls' facial expressions and body language.  You can pick up on tension and dissolve it before the girls notice.

One note from a concerned mom.  I don't appreciate when my kids come home and tell me they've watched a movie I wouldn't have allowed them to watch. I am working with my kids on calling home to ask permission, but I'd appreciate it if parents would give me a heads up on what they will view.  On the invitations to this sleepover, I did give an overview of what we would be doing, including which movies we would watch.