"The average woman today doesn't sew as well as the average 8-year-old of 100 years ago," says Joan Hoffman, a member of the Herndon/Reston Piece and Patch quilting group. "In those days, it didn't matter if you were rich or poor -- every woman quilted. It was one of the things a woman's life was all about, and a way to be proud of yourself."

With the advent of central heating and the Industrial Revolution, quilt-making slipped from a necessity for the many to an enthusiasm for the few. But Hoffman says "We need craft today more than we did in our great-grandmothers' time. In this push-button age, we need something to retreat to."

More and more Northern Virginians are finding that quilting is a good "retreat." There are no fewer than 17 quilting groups in the area, involving perhaps 1,000 quilters. Many learned the craft from friends, neighbors or books, though a few, such as Hoffman, learned it through family tradition.

"My grandmother's wedding quilt is on my bed," she says, "and it makes me feel close to her."

Hoffman hopes a few of her many quilts will be passed down to her grandchildren and great-grandchildren, "so they can say, 'my grandma made that -- those were her stiches, these were the colors she picked.'"

Whether it's a sense of heritage in the making, an outlet for perfectionism or just "something a woman can do that won't immediately become undone," as one quilter put it, the craft seems to be habit-forming. At a quilting bee thrown last Sunday by the Fairfax County Park Authority and Hoffman's quilting group at Colvin Run Mill, quilters confirmed all these impressions.

"I call it 'quilt pox,'" says Cheri Clum of Falls Church. "Once you've finished one quilt, you can't stop."

Quilting is a partial misnomer since it describes only half the process. The first step is to make a "top," or covering layer, usually by arranging bits of cloth into a predetermined pattern.

The pattern names are inspired by the designs they form or by associations. A row of squares is called "Jacob's Ladder" today, but it was "Road to California" during the Depression; a design with a large square as a centerpiece is called "Boston Commons"; small and large triangles are dubbed "Fox and Geese"; and an irregular, shaky-looking cross is called "Drunkard's Pass."

Once the pieces are all sewn together, either by hand or by machine (even the Amish use machines to piece these days), the quilt "sandwich" is made. A bottom layer, today usually made from plain sheeting, is laid down and covered with a layer of batting. Polyester is the batting material of choice these days, although our foremothers used cotton, wool, "and even leaves or cornshucks -- anything they could find," Hoffman said.

The top piece goes over this layer of insulation, and the whole thing is stretched over a frame. Quilters use everything from oversized embroidery hoops to room-sized frames.

Starting from the middle of the quilt, traditionally, the quilters "run the ditch" (follow the seam marks), or follow a pattern they have drawn onto the quilt. On many quilts, both techniques are used.

Regional differences show up in all these techniques. "Northern women couldn't stand to waste any scrap of material -- that's where you get your 'crazy quilts,' with all funny shapes and materials pieced together," says Hoffman. "Southern quilts are easy to tell because the women had slaves to pick the seeds out of cotton, and more time on their hands to do more intricate work."

All early-American women were expected to complete 12 quilts before they reached marriageable age -- no small feat, when you consider that a good quilt takes 250 to 500 hours to make, says Hoffman. "I was paid $ 100 for one of the first quilts I made -- I figure I earned about 20 cents an hour."

Emily McCarthy, another quilter in the Herndon-Reston group, says money is no measure of the craft. "This is not just a time investment, it's an investment of your life. You look at the quilts and say, 'I was pregnant when I made this one; we had just moved when I started that one.'"

Many women sew personal mementoes into their quilts: bits of old maternity clothes, parts of their children's jeans and dresses. Cheri Clum had everyone at her wedding sign quilting blocks, then stitched the signatures into a quilt.

The reward from such personalized work is an "emotional satisfaction that it's almost impossible to get in this high-technology era," says Hoffman.

Two major quilting associations have chapters in Northern Virginia, from Springfield to Hamilton. To find one near you, contact:

* National Quilting Association, P.O. Box 62, Greenbelt, Md. 20070.

* Dorothy Holden, director of Quilters Unlimited, McLean telephone 356-1959.

An independent group meets at the Martha Washington Library in Belhaven; call Barbara Zygiel at 765-9510 for more information. Nelly's Needlers, a sewing group that supports Woodlawn Plantation, reproduces antique quilt patterns; telephone 557-7881.