Left to their own devices, most kids will find a way to entertain themselves — but their idea of a good time may do irreparable harm to your living room. Control the chaos by planning activities that will keep them laughing (and keep your furniture intact). Be sure to plan more activities than you think you'll need. That way you can move quickly to something else if guests lose interest.
Guests won't all arrive at the same time, so prepare some open-ended activities that will keep children busy as they wait. A big box of dress-ups that fit your theme, like scarves and shields for a medieval festival or tutus for a ballerina party, will get everyone into the spirit of the day. This will be even more effective if you have a big mirror and a Polaroid camera on hand so the guests can admire themselves. You can also use a digital camera to create an instant slideshow to run on your computer.
If the children don't all know each other, be sure you (or the guest of honor, if he's old enough) make introductions. Wait until everyone arrives to begin games that require rules or crafts that need supervision.
Simple games work best for young children, but you may worry that they aren't exciting enough for a party. Remember, however, that kids love tradition and may feel that the party is incomplete without a round of Pin the Tail on the Donkey or Follow the Leader. Never fear: you can reconcile your child's desire for repetition with your quest for creativity by updating old favorites with a personal twist.
Sesame Street fans will love Pin the Beak on Big Bird or Where's Elmo?, in which guests have to look for a hidden Elmo while adults yell "hot" or "cold." You can also play Hot Elmo (like Hot Potato) in which guests stand in a circle and pass around a toy Elmo until the music stops (play Elmo's "Hot! Hot! Hot!" dance song if available). The child caught with the toy in her hand when the music stops is out.
The disadvantage of single-player games (like Pin the Tail) and elimination games (like Musical Chairs or Hot Potato) is that you need to provide an alternate activity for the kids who aren't playing.
Vary the rhythm to include both quiet and active games so kids don't become over-stimulated. If you have enough room or are hosting the party outdoors, you can plan a silly obstacle course (http://pbskids.org/zoom/activities/games/eggstaclecourse.html) or wacky relay race (http://pbskids.org/zoom/activities/games/toewritingrelay.html). Adding a crazy element to the races should keep players from taking them too seriously. Try a backpack relay (http://pbskids.org/zoom/activities/games/backpackrelay.html), in which team members have to run to a destination with a pack that is full of funny items, unpack them, perform a task, and run back to the starting line.
It's best to include some noncompetitive games so no one feels frustrated about not winning. Try Popping for Presents, in which you slip small papers with numbers on them into balloons — one for each guest — before you inflate them. The kids have to sit on balloons to break them; the numbers correspond to small prizes.
Children over seven or eight will be ready for more sophisticated games, like a treasure hunt or detective game instead of a simple hiding game. One mom gave her treasure hunt a prehistoric twist by printing out "cave drawing" maps and hiding plastic dinosaur eggs filled with jelly beans around the yard for a dinosaur bash. As with all games, the activity itself is far more important than any treasure you hide.
Crafts are a great way to involve all your party guests. There's no competition and kids can take home a special favor they've made themselves.
Even young children can make simple crafts like a drinking straw necklace (http://pbskids.org/rogers/R_house/object21.htm) or giant self-portraits (http://pbskids.org/teletubbies/parentsteachers/offline/offact45.html) on butcher paper. Handprint shirts (or handkerchiefs) are also popular: Just have each child dip his or her hand (or foot) in fabric paint and leave a print on an inexpensive white T-shirt. Use a fabric pen to write the child's name next to the print.
Older children will be ready for more sophisticated projects such as tie-dyed socks (http://pbskids.org/zoom/activities/do/tiedyedsocks.html) or T-shirts. Be careful not to make the crafts too complicated for the guests or you'll all get frustrated. Done well, the right craft makes a delightful party favor (and eliminates the need for goody bags).
Many children (including the birthday child) may feel overwhelmed after all the games. It's best to arrange a calming activity for children as they wait to be picked up. Consider supplying sticker books, quiet games (http://pbskids.org/lions/printables/), coloring pages (http://pbskids.org/jayjay/colr.book.html) or some simple card games like Go Fish or Old Maid to keep goodbyes happy.
After all the weeks of planning and excitement, many birthday boys and girls feel let down once the party is over. Consider asking one special friend to stay behind (you'll need to arrange this with a parent ahead of time) when all the guests leave to help your child make the transition.