Hecht's department stores have stocked thousands of extra evening dresses. Wal-Marts are displaying Millennium Barbies and "Millennium Party Mix" CDs--as well as shelves filled with bottled water, batteries and flashlights.

For more than a year, the nation's retailers have been wringing their hands, trying to predict how consumers will behave in what promises to be a strange holiday shopping season. They have stocked up not only for bigger and more prosperous Christmas crowds but also for record numbers of New Year's Eve revelers and shoppers who fear coming disaster from year 2000 computer glitches.

Now that the planning stage is over, merchants must worry about sales in stores overflowing with extra Christmas toys, year 2000 T-shirts and generators powerful enough to supply electricity to an entire home.

"At this stage, they've done what can be done," said Cathy Hotka, information technology vice president for the National Retail Federation. "All we're doing now is holding our breath and telling customers, 'Please, come shop.' "

And if they do come in the expected numbers, shoppers will see the usual holiday checkout lines grow even longer as all three groups--the Christmas crowd, New Year's partiers and Y2K worriers--collide in the aisles.

So far, consumers have had mixed reactions to what's on the shelves. At Hecht's, they are eagerly buying sweaters and jewelry as gifts, as well as thousands of ball-gown skirts for New Year's Eve parties. They are snapping up millennial picture frames and Waterford champagne flutes.

But by many accounts, the gimmicky year 2000 baseball caps, teddy bears, mugs and key chains will end up on the clearance racks in stores across the country. "Remember that merchandise that came in and had '01/01/00' on it?" asked Nancy Chistolini, a spokeswoman for Hecht's. "That didn't do well. . . . I think people wanted it to be a little bit more serious."

John Konarski, senior vice president for the International Council of Shopping Centers in New York, said the question about year 2000 souvenir stock is: "Will enough of it sell to cover the incredible amount of merchandise out there? I don't think so. I don't think it will ruin anyone, but it may eat into some companies' profit margins."

Some retailers restrained themselves, offering only a small selection of goods bearing the words "Year 2000." Crate & Barrel stores, for instance, decided to carry only a set of four millennium champagne flutes for $19.95 and a set of six glasses for $17.95.

"For our customer, we didn't think they'd go for anything that was too cutesy," said Bette Kahn, a spokeswoman for Crate & Barrel.

Beyond souvenirs, enough people around the country are stocking up on Y2K supplies to account for significant increases in sales of generators, fuel-storage tanks, camping equipment and ammunition, said Kenneth M. Gassman Jr., a retail analyst with the investment firm Davenport & Co. in Richmond.

"All year long, there has been an undercurrent of Y2K demand, mostly from survivalists but some of it from mainstream groups," Gassman said.

The demand has been spotty, however. Officials of Wal-Mart Stores Inc., for example, say that they carefully prepared for increased purchases of Y2K items such as bottled water and batteries but that shoppers don't seem much concerned about the calendar change. "There are a few different categories that have seen some increases," said Les Copeland, a Wal-Mart spokesman. "But overall it's just benign."

Sales of survival items have been most brisk outside major urban areas such as the Washington region, according to industry analysts. Several local merchants said they had expected increased demand for generators after hearing about booming sales of Y2K equipment elsewhere. But few area residents, they said, seem interested.

"I don't see it," said Rick Leary, general manager of Coleman Powersport in Falls Church. "Maybe it's too early. Maybe people are smarter."

Still, many merchants aren't quite ready to pull back.

Food Lion, which operates many grocery stores in rural areas, has said it may see a large spending spree in the last two weeks of the year. It has prepared its stores accordingly, bringing in extra bottled water and canned food that comes in economy boxes.

"It does make the stores very full, combining what people normally buy for the holiday and having products for people who choose to stock up," said Chris Ahearn, a spokeswoman for Salisbury, N.C.-based Food Lion.

Even urban consumers who act jaded about the Y2K issue may switch gears at the last minute--and that's something retailers say they have to be prepared for in late December.

"I think even people who are not interested in Y2K, somewhere in the back of their heads they're saying they may pick up a few extra items, just in case," said Greg Turner, senior vice president of merchandising for Home Depot Inc., an Atlanta-based home-improvement chain.

Home Depot is readying itself for last-minute buyers, stocking its stores with more than double the amount of batteries it usually carries and twice as many flashlights.

In upcoming weeks, consumers can expect year 2000 partiers and stockpilers to create even longer lines at stores, analysts said. But even without those extra shoppers, shops would still be packed. Thanks to a robust economy and booming stock markets, analysts are calling for retail sales to climb 5 percent or more during the last two months of the year.

Both analysts and retailers also expect unusual surges in buying during the week after Christmas.

"We think everybody is going to go to the store on Dec. 28," Hotka said. "There will be a million people in the store. And they'll get a few extra cans of food, batteries and flashlights."

What happens right after the clock ticks into the new year is anyone's guess. Federal and retail experts foresee no widespread outages and thus don't anticipate a panicked rush into the stores. But some analysts expect a mini-boom in sales because people who hoard cash before Jan. 1 may decide to take the money with them on a spree at the mall rather than a trip to the bank.

Others aren't as optimistic. Wal-Mart chief executive David D. Glass warned that January sales could be soft because consumers who have stored food anticipating year 2000 problems will not need to shop as frequently.

Then there's the returns factor. If there's no meltdown of the power grid on Jan. 1, what happens if lots of people try to bring their unopened generators back to the stores for refunds?

Many stores are trying to discourage such thinking. Sears, Roebuck and Co. will impose a 20 percent "restocking fee" on anyone who returns a working generator.

Small hardware stores are posting signs that read "absolutely no refunds on generators" and warning customers that what they buy is theirs forever.

"We know they'll come back with a million stories about why they don't like it," said Ed Morris, owner of Morris True Value Hardware in Salisbury, Md. "It's not large enough for their needs. 'I don't like the way it runs.' 'My wife doesn't like it.' "

Excuses won't work, however. "We're holding the hard line," Morris said.

CAPTION: Preparing for the holidays and perhaps beyond, shoppers at the Hecht's department store at Tysons Corner crowd the men's department at noon yesterday.

CAPTION: Brooke Hudgins looks at a millennium gown at the Tysons Corner Hecht's.