Whatever you choose to do for the big celebration, it may be wise to let older birthday boys and girls in on some of the planning.

"There's a competitiveness that kids are all quite conscious of," says Diana Zurer, a D.C. mother of three boys. "It's difficult for children to understand when you can't give them exactly want they want for their birthdays. They say, 'This one had a sleep-over, plus they went to Farrells, plus they went to a movie after that.'

"So you collaborate. They say what they want to do and I tell them how many they can invite."

While it's easy to go overboard, limits can be set by computing number of guests, favors and entertainment and come up with a party your budget can handle.

"It's important to spend time talking it out with the child," says Rose Spiro, Alexandria. Her son decides how many children he'd like to have and some of the things he'd like to do. "I do some research on what it costs and give him some choices. I tell him he can take five children to the movies or eight bowling."

Even the most carefully planned party can have some disasters. Here are some additional hints gleaned from experienced mothers:

Alternative plans. What do you do if the entertainment is late or the Moon Bounce loses its air in the backyard? Put on marching music and have a parade around the house. Have a relay race. Eat, read, tell a story. Play football in the back yard. Dance. Write four-syllable words on paper and have children extract smaller words from them. Make hats out of newspaper.

Organization. Plan for every minute the children will be at your house. "It's like being a teacher and having a lesson plan," says one mother. "From 2 to 2:15 p.m., open presents, from 2:15 to 2:40, play Pin the Tail on the Donkey, etc."

Guests. Never invite more than the age of your child. Children get confused at young ages and the noise and excitement may be overwhelming.

Food. Lots of treats for older kids, very little for younger: They'll end up playing with, rather than eating, their food.

Favors. Buy inexpensive dime-store trinkets: bubble blowers, snoopy pencils, pinwheels. "What's tacky to parents is not necessarily tacky for children," says Zurer. "I once gave packages of flower seeds, which turned out to be more charming for mothers than children."

And forget the cute hats for very young children. They don't like to wear them.