The hardest part of holiday entertaining is not the sit-down dinner for 20 or cocktails for 50. It is entertaining the children on the day before Christmas.

The same Christmas that is coming toward you at a rush is approaching them at a crawl. Instead of letting Christmas Eve get out of hand, with nagging, whining children underfoot, plan it the way you would any party. Control the day instead of letting it control you.

If you have parents visiting, let the two generations entertain each other, sending them off to explore Washington. If you are on your own as a child-minder, try to work a trade with a friend -- one of you takes all the children for the morning, the other for the afternoon. You are much more likely to get shopping, cooking and wrapping done in half a day that is entirely your own than in a whole day cluttered with over-excited children.

Plan the day so that the children stay busy and get tired enough so that they actually go to sleep after they've been tucked into bed. This morning, lead the band out in search of reindeer (though, if you live in a neighborhood given to understated good taste, you may have to substitute caroling instead). Spot the reindeer on the lawn, the reindeer in the window, the reindeer on the roof -- laurels to the child who spots the most reindeer first.

After the walk -- a long one -- pop enough popcorn to fill two bowls, one for eating and one to be used for decoration. Provide needles with long, heavy-duty thread and let the children create strings for the Christmas tree -- two popcorn kernels, two bright red cranberries until the string is of a length to drape around the Christmas tree.

When they tire of that -- and pushing a needle through popcorn will not enchant them for long -- be ready with the next project, a Christmas play. Let the children make up the play and assign the roles themselves. Rehearsals can fill the rest of the morning, with the play scheduled for a performance just before dinner, when the trade-off parents show up to get their offspring.

When it is time for lunch, let the children make their own, using Christmas cookie cutters to shape their sandwiches into stars or trees. Challenge them to produce a red-and-green lunch: sandwiches of strawberry jam and a green apple, or tuna salad tinted with green food dye. Afterward, give them small chunks of suet tied with string and send them out to shinny up the trees, decorating the branches with Christmas treats for the birds.

After lunch there is a changing of the guard, with the morning child-minder set free and the afternoon person taking over.

Get out the bits of wrapping paper and ribbon which you save every year even though they are too small or too ratty to ever use again. Give these to the children and send them off to decorate dolls, stuffed toys and doll houses for Christmas.

Just about now you will discover that even though you bought far more wrapping paper than you could possibly use, you do not have enough. And no one ever has enough name tags for the gifts. So get out crayons or paints, unroll a roll of white shelf-lining paper and set the children to work designing extra wrapping paper. (This is a project best done in the basement.) When they have decorated a whole roll, give them a pile of old shirt cardboards and set them to cutting out and designing name tags.

In the morning, while you were out shopping, you will have cunningly bought a small gift for each of the children, wrapped it and hidden it outdoors. Each child is given a clue to where his own special gift is hidden and then sent off on a long, tiring search to find it.

Time for hot chocolate and Christmas cookies, which, if the children are old enough, they may bake themselves. It is Christmas Eve, after all, and if they are told that being designated good boys or girls depends on their cleaning up afterward, chances are that, today at least, they will.

Then the cookies must be sampled, and a plate arranged for Santa Claus' midnight snack -- cookies and milk and sandwiches cut out with cookie cutters.

After this it will be time for one last run-through of the Christmas play. Following that is the premiere performance with the two sets of parents sharing a glass of Christmas cheer, as a reward for being such creative hosts.

Next dinner and then, to help the children settle down, some Christmas music on the phonograph, and a family reading of a Christmas classic: Dylan Thomas' A Child's Christmas in Wales, or Dickens' A Christmas Carol, or 'Twas the Night Before Christmas.

Finally, with Santa's plate tucked away under the tree and the children tucked away in bed, you can all settle down for a long winter's nap.