Is your home too small? Don't tell Mary Elizabeth Williams, her husband, Jeff, and their two daughters, ages 5 and 9.

In 2006, the New York couple paid $360,000 for a 800-square-foot co-op in the Manhattan neighborhood of Inwood. Divide that square footage by four people, and they average 200 square feet per person. According to a 2004 report by the Heritage Foundation, the average American has 721 feet apiece, while the average poor American has 439 square feet.

Williams actually felt lucky to get their co-op because now their daughters share a 7-by-11-foot bedroom -- with a door, unlike their alcove in the family's previous apartment.

Nevertheless, the kitchen is galley-like at 10 by 7 feet and they call their dining area the "dining gallery."

"There are times when I have literal traffic jams between the kitchen and bathroom. There's a child standing right there," says Williams, author a new book, Gimme Shelter: My Three Years Searching For the American Dream. "You are shimmying around all day."

How do they manage in a small space?

"I'm really insane about purging and picking up the clutter," she explains. "And I have an obsession with the Container Store."

Since floor space is limited, she favors storage containers that go up -- tall bookcases and lots of shelves. It also helps to be very meticulous about the items that come into the home.

"That's how most people in the world live," she says. "When you think about it, 3,000 square feet is kind of ridiculous. I like being really zen. The things I have I really love."

For instance, she has a shoe rack that holds 12 pairs. "That's how many I have," she says. "I'm not going to have more. That's my life. It's a no brainer."

While keeping clutter down can be especially difficult with children around, they have made it work. "My daughters don't get a new toy until we give one toy away."

She also likes the fact that her children are within earshot at all times. "The practicality of staying here with kids when they are bigger kind of freaks me out," she says. "But for the foreseeable future, the idea of moving -- noooo!"