Mary Moran, an executive assistant at a government commission, does it. Michael Sims, a commercial real estate broker, does it. So do U.S. Senate employee Beckie Whitehead, Catholic University student Daniela Manville and lawyer David Godschalk.

They all go shopping online while at work.

"Everybody does it," said Lara Swett, an administrative assistant at the National Petrochemical and Refiners Association.

The Friday after Thanksgiving may be the kickoff of the holiday shopping season in malls and stores, but online, the big day is the Monday after Thanksgiving -- today -- when people go back to work.

"Thanksgiving is when we get lists of what family members want," said Tresa Undem, an analyst with Lake Research Partners, a District-based polling firm. So she'll go back to the office today and start checking things off her list, probably in the afternoon when she needs a little break from her polling projects. "We all work hard, so if we spend 10 minutes shopping," she said, "I don't think it's a big deal."

The online retail industry has taken to calling today Cyber Monday or Black Monday, named after Black Friday, when many retailers traditionally have started to make a profit -- or go into the black -- for the year. In a recent survey by Shop.org and BizRate Research, 77 percent of retailers reported that their sales last year increased substantially on the Monday after Thanksgiving.

The growing phenomenon is an intensification of the year-round surge of online shopping during the workweek, changing the workplace as much as shopping patterns. At QVC.com, for example, Mondays are almost always the biggest shopping day of the week, said spokeswoman Bonnie Clark. For Visa, which processes 47 percent of all online purchases, weekdays bring much higher volume than weekends -- the exact opposite of typical traffic patterns in regular retail stores. The workweek after Thanksgiving is Visa's highest-volume week of the year.

"I'd love to see that chart -- workplace productivity versus sales," joked Brad Nightengale, vice president of emerging products for Visa USA.

The biggest online sales day of this year so far, as tracked by Visa, was Nov. 15 -- a Tuesday. But the peaks are yet to come, with 20 percent of Visa's annual online volume typically logged from Thanksgiving to year-end, Nightengale said.

Experts say this week will bring the biggest online shopping burst ever, because holiday clicking and shipping is predicted to jump by 25 to 30 percent over last year.

Industry experts say consumers spend their weekends window shopping, talking to friends, and getting ideas about what they need and want. Then they head back to work, where they have high-speed Internet connections and tempting moments of downtime. Many workers say they put in such long hours at the office, it's the only time they can shop online. At home, there's just too much to do.

"I'm at work more than I'm at home," said Mary Moran, an executive assistant at the Appalachian Regional Commission, who has already done all her gift buying online, at work.

Postell Carter, a database manager for the New Israel Fund in the District, squeezes online shopping trips into his day in bits and pieces. "Generally every couple of hours I'll take a little break," he said, adding that he might go online to buy clothes for his kids or flowers for his wife. It rarely takes more than 10 minutes, he said.

He plans to start his Christmas shopping in earnest this week.

Carter said his boss is easygoing about online shopping, as employers increasingly are. Several major local companies said they are fine with employees doing personal errands on the job as long as they do not abuse the privilege.

"We actually think it's productive if they do it that way instead of running out to a suburban mall and stretching the one-hour lunch into two," said Bob Dobkin, a spokesman for Pepco, which has 2,500 employees in the area. "We do think it promotes a better employee relationship."

Workplace consultants say employers' attitudes about online shopping are evolving, generally in favor of giving more leeway to employees. Where many companies once blocked access to high-volume shopping sites, for example, they now use threshold software that simply limits an employee's time on such sites, said Susan Larson, vice president of global threat analysis and research for SurfControl, which makes filtering software for workplaces. Today, she said, companies are more worried about employees bringing viruses into an office network by shopping online than they are about reduced productivity.

This approach is good for the company and employees, said John A. Challenger, chief executive of executive recruiting and consulting firm Challenger, Gray & Christmas.

"Allowing people to do some of their personal work at work is just good policy," he said. "That blurring of work and personal life really has completely changed the way we think about work. It's no longer true that when you're at your desk from 9 to 5 you're at work, and when you're not at that place you're on your personal time."

This season, workplace Web shopping is abetted by high gas prices, which are keeping some people from driving to malls. Also, retailers are getting more sophisticated about integrating their Web sites into their regular business. At Talbots.com, for example, a new feature this year allows shoppers to browse online and reserve what they want at a nearby store.

"It's like having this huge door that's just open 24-7, everywhere," said Betsy D. Thompson, fashion spokeswoman for Talbots.

Of course, to say absolutely everyone shops online while at work does not give due respect to those who never shop at work. Adam Hyland, a wine consultant at Paul's Wine & Liquors in Friendship Heights in Northwest Washington, said he just does not have time, even though he is on the computer off and on all day. "I'm doing work things," he said, almost sheepishly.

Hyland does shop online, at night, at home, with a high-speed connection. But it's not Christmas shopping.

"I usually let that go to the last two weeks," he said. "That's when I end up at Tysons."

Postell Carter shops and listens to music while at work. While at his job, he rarely spends more than 10 minutes at a time shopping.