After years of shuttling her kids to Saturday afternoon birthday parties, Becky Hart was surprised by the invitation that came addressed to her 7-year old, Claire, last month.

For: One of Claire's classmates

Where: Chuck E. Cheese

When: A Wednesday night.

"At first I thought it was kind of strange that it was at night," said Hart, who, despite her reservations, bought an Irish setter Webkinz and wrapped it in pink princess paper for her daughter to take to the school-night bash.

Two hours later, her daughter left pleasantly stuffed with pizza, and Hart said she began to reconsider the assumption that kids' parties should all be squeezed into already overbooked weekends.

"We always have something going on. She's always doing something: soccer and ballet," said Hart. "In the summer, it might work really well."

Like Hart, many parents have strayed from the Saturday-only birthday rule to consider midweek birthday celebrations. Popular party destinations across the country report an increase in kids' parties booked Mondays through Thursdays.

One obvious reason is financial: Companies that specialize in kids' parties have dropped prices and added incentives for parents who book weeknight parties. Parents save money, and struggling businesses make money on what would ordinarily be slow nights.

But parents and experts who study parenting habits say the weeknight parties may also point to a shift in the way moms and dads view birthday celebrating.

While there will always be parents who insist on weekend parties — or take them to the extreme a la MTV's "My Super Sweet 16" — many parents seem to be returning to party-throwing habits of the 1970s and 1980s, with smaller parties thrown on a child's birthday. That acknowledges kids' busy schedules and keeps the children grounded, said Lisa Kothari, author of "Peppers and Pollywogs — What Parents Want To Know About Planning Their Kids' Parties."

"It's bringing us back to a simpler time, but at the same time the celebrations are still wonderful," said Kothari. "The competition of wanting to get people to come to your party is not as great."

Claudine Schramko of Hinsdale, Ill., was happy when she realized that her 10-year-old daughter Emma's birthday — April 8 — fell on the Wednesday before spring break this year. Without hesitation, Schramko booked a party for Emma at Sweet & Sassy, a salon and girls' accessory store.

Days before the event, Emma's friends talked giddily on the phone about the upcoming party. At school that day, girls counted down the seconds until the final bell. By the time all 11 girls arrived and put on sparkly tiaras, feather boas and sequin dresses, Emma and her friends' excited squeals were louder than the "High School Musical" songs pumping out of the speakers.

"I couldn't wait for it all day. I was just like, 'I can't wait until school's over,' " said Bryn Latimar, one of Emma's classmates.

The birthday girl explained that she and her classmates liked having a reward for their busy schoolwork.

"Sometimes, when we're in school, we're usually studying, so when we come here, we can have something fun," she said.