Inside the Alexandria home of Daniel and Patricia Donnelly are all the trendy trappings featured in shelter magazines these days: Eames chairs, tubular metal tables, squared-off sofas. This is the type of hard-edged stuff that looks hip but hard to live with, especially if you have kids.

The Donnellys, as it turns out, have managed to maintain the cool look while keeping it comfortable for themselves and their two young sons. The couple seem to have adopted the design philosophy of "form follows family" in furnishing their home with modern pieces from the 1930s, '40s and '50s.

These finds represent years of foraging through auctions, flea markets and dusty basements. But Dan and Pat are no ordinary collectors. They own one of the few stores in the Washington area specializing in 20th-century furnishings. And their mania for all things modern isn't a recently acquired taste.

In the late 1980s, when shabby chic was all the rage, Dan Donnelly was selling streamlined, art deco furnishings in Alexandria's Old Town; his store, Daniel Donnelly Modern Design Studio, is now located in a warehouse on N. Fayette Street.

"My parents had an antiques business, and I couldn't stand all the ugly brown furniture we handled, the Duncan Phyfe and Chippendale reproductions," he says in explaining his passion for modern design. "I was more drawn to the Depression era's cleaner, simpler philosophy."

By the mid-'90s, Donnelly's specialty had become vintage and reproduction furniture of the 1940s and '50s, plus new furnishings he designed based on those mid-century styles. While building the business, Dan and Pat were renters until plans to have children led them on a hunt for a home that would provide the right backdrop for their favorite 20th-century treasures. Their search led to a 1939 house for sale in Alexandria's Beverley Hills neighborhood.

"It was painted a weird flesh color and had been Spanish Colonial-ized," recalls Pat. "But I could see it had modern bones underneath."

After moving in, the couple took the house back to its art deco roots by reinstating the glass-block wall framing the entrance and painting the exterior a pristine white. Inside, original features were similarly restored and replaced to reinforce the deco feeling. In the front hall, the staircase was modernized with an aluminum balustrade from the SS United States, an ocean liner launched in 1952. Furnishings were drawn from Dan's favorite stash of aluminum designs from the 1930s and '40s, including banded pieces by Los Angeles furniture maker Warren McArthur, some of which almost look like they are made of bamboo.

Like most collectors, the Donnellys proudly relate where they found each piece. The vinyl-upholstered Eames chairs around the Parsons-style dining table, Dan says, were purchased from the estate of noted modern clockmaker Howard Miller, son of famous furniture manufacturer Herman Miller. Though the pieces are carefully arranged, the feeling is relaxed, not rarified.

"It's modern furniture that's kid-friendly because there are a lot of curved edges," says Pat. "We use the living room for practically everything."

Demonstrating their mother's point, sons John, 7, and David, 4, jump onto the long, ultrasuede sofa, which Dan Donnelly designed, that hugs the living room wall.

"This table taught John how to walk," says Dan Donnelly, pointing to one of the squiggle-shaped coffee tables in the living room. He recalls how his young son supported himself on its curved cork rim while taking his first steps.

This summer, the Donnelly family spent a lot of time outdoors enjoying their newly built swimming pool in the back yard, surrounded by Bertoia mesh furniture and potted palms.

Nearly every Tuesday afternoon, Pat says, neighborhood moms and kids are invited over for pizza and a dip.

"It's become the neighborhood pool, a place to hang out and have fun," says Pat. "We call it Camp Donnelly."

Deborah K. Dietsch is the author of Classic Modern: Midcentury Modern at Home.