How nice to be disguised, to be able to abandon the everyday self and don a costume to suit the occasion. Most of the year, it is a simple switch from day clothes to evening -- a bit of glitter, a dash of de'colletage for the women, a dinner jacket and a satin cummerbund for the men and a floppy bow for the family dog. Thus transformed, everyone is ready to have a good time. But on at least one night of the year, the disguise can go beyond feathers and furbelows. On Halloween we can transform completely into figures out of a dream or a nightmare.

Easiest is simply to ask everyone to come to a Halloween party wearing costumes, though it's actually a bit late to issue that kind of invitation, since by now the rental stores will have a depleted stock. But a little creative thinking makes it possible to give a last-minute costume party. For instance:

Make it a mad-hatter's party, asking everyone to show up in a mask and a hat -- well, not just a mask and a hat unless you want to shock the world with a Profumo party, but the rest of the dress can be everyday ordinary.

There is so much scope with hats -- bowlers or fez's, sombreros or pillboxes, straw boaters, sailor hats, massive broad-brimmed leghorns trimmed with fruit and flowers, hats resembling birds' nests or a soldier's kepi, cowboy hats and Indian headdresses. And hats are easy to find. Any junk shop or secondhand clothing store will turn up a wonderful array.

If you think your friends are too busy getting on in the world to take the time, set aside a day to search out old hats to hand out as guests arrive. Even if you have a large group of friends coming to join you on the witching night, it won't cost that much money. Until the day someone thinks to call them antiques, cast-off hats will not command high prices.

Have a bits-and-pieces costume party, asking everyone to bring one item of cast-off evening clothes, old jewelry, feathers, any item which once took their fancy but which they now are happy to part with.

Stack all the contributions in one room and let each guest rummage a costume. Anyone who spent the rainy days of childhood playing dress-up in the attic will be able to emerge in appropriate Halloween garb.

Ask guests to come dressed not as a person, but a place. Those who are too busy to bother can satisfy the demand by showing up with a street map of Washington pinned to their chests. More imaginative folks could wear a necklace of yellow stones (Yellowstone National Park), a billboard-like costume representing a New York skyscraper, dozens of little mirrors to become the Hall of Mirrors at Versailles, a large clock face tacked across their back (Big Ben in London), or a collage of store titles cut out of the newspaper so that the consummate consumer could arrive dressed as a shopping mall. The hopelessly lazy guest can wear any item of clothing that has been stained and explain that this is his favorite spot.

For insight into the fantasy life of those you've invited, ask them to come dressed the way they see themselves 10 years in the future. The modest may come dressed as bag ladies or bums, but in Washington one is sure to unearth at least one president.

Light the house with jack-o'-lanterns, but instead of the standard grinning pumpkin head, try carving small patterns in the pumpkin for the candlelight to shine through. An X-Acto knife will give you more control than a paring knife, though you may need the latter to finish the job. Don't cut out so much shell that the pumpkin collapses. And, speaking of pumpkins ... if you are going to serve pumpkin soup cooked in the shell, for heaven's sake keep an eye on it. If the shell overcooks, the sides of the pumpkin will fall in on themselves, and unless you hurriedly ladle the soup into a backup bowl you will have a major mess and no first course.

In addition to pumpkin soup, and the traditional pumpkin pie, there are pumpkin mousses and pumpkin breads and pumpkin cookies -- pumpkin can double in any recipe calling for winter squash. Ask at the supermarket or the roadside stand for the smaller sugar pumpkins, which are grown for eating, not the larger jack-o'-lanterns that have a watery, stringy meat.

And don't become so intent on a theme that you forget to provide sustenance. Fantasy is all very well, but even the Statue of Liberty needs to eat.