COLLEGE PARK - Allow Rob Sherwood to explain his assignment. "I buy pizza for people," the University of Maryland graduate student says.

Sherwood is Google's official pizza ambassador at the university, which means he essentially has a blank check from the Internet-search company to buy his classmates pepperoni pies.

Google officials aren't paying for the food out of the goodness of their hearts. The company is always on the lookout for up-and-coming computer programming talent, and it apparently figures that the inventor of the next generation of Gmail might think of Google fondly because a few slices tided her over during midterms.

There are a few stipulations. The food is meant for computer science or engineering students. Liberal arts majors need not apply. No subs or Chinese food. The purchase has to be made at a stressful time, such as around midterms or when big projects are being finished by students working in groups late at night.

And when you chow down, please try and use plates and napkins with the Google logo and take a picture to post on the Web.

Those conditions are just a slight inconvenience for free food, most students say, and beat other recruiting giveaways that are so common this time of year, such as mouse pads, rulers, pens. "We have plenty of pens," Sherwood said. "You can't eat one."

Paying for pizza was the brainchild of some Google engineers about three years ago, according to company officials, who answered questions only by e-mail and wouldn't disclose how much the program costs.

Student ambassadors say they get $500 at the start of each school year and are sent more when that runs out. They have never been told to watch costs, they say. Nearly 100 ambassadors are on campuses nationwide, Google officials said.

No matter how much pizza students can scarf down, it's doubtful it would make much of a dent in Google's finances. Last year, the Mountain View, Calif.-based company made almost $3.2 billion.

The pizza program came to the University of Maryland about a year ago. William Pugh, a computer science professor, had done consulting work with Google and had heard about the ambassadors.

"The idea of students up late and on deadline and having pizza is pretty typical; it plays into the standard myth of college students. But the students seem to really like it," he said.

One of Google's founders, Sergey Brin, graduated from the University of Maryland in 1993. ("He was obviously one of the brightest students, but there wasn't anything at the time that made me think he was going to form a multibillion startup," Pugh said.)

Despite its hometown advantage, UM was not one of the original schools in the program.

When Sherwood became the pizza ambassador, a volunteer position, he sent an e-mail to the computer science department to tell students about the free food. There was a fair amount of disbelief at first, Sherwood said.

"People giving me money or free things usually makes me skeptical. There's usually some kind of catch. A lot of people think like that," Sherwood said.

There was also confusion about how the program works, Sherwood said. "There were questions like, 'Well, I'm having class with my friends. Does this count as a stress time?'"

No. Sherwood said he received no instructions from Google about what qualifies as a stressful time, but he decided that just being in a class doesn't qualify. "My attitude is, it's such a good thing that it's not worth our while to take advantage of it and cheat the system," he said.

Students have become more familiar with the system, and Sherwood said he almost never turns down a request. He has run through the original $500 and then some, and finals are just around the corner.

Most UM pizza parties are relatively small. Four or five people order a few pies and some Coke, and the bill is generally less than $60. The students give Sherwood the receipt for their purchase, and he reimburses them.

"It generally works out that the people who are having the pizza already know each other," Sherwood said.

It doesn't work that way everywhere. At Carnegie Mellon University in Pittsburgh, ambassador Matthew Laroche orders up to 10 pizzas at a time when he gets a request. "I prefer to do things on a bigger scale," he said.

Laroche, a junior computer science major, said he tries to tell as many people as he can before the pizza arrives. "I can't exactly limit who gets pizza, and I'm not sure I'd want to anyway," he said. "If a computer science student comes by, I'll say, 'Sure, have some.'"

Google declines to say how many of its employees noted the pizza program as a reason for working at the company, or how many came from schools with pizza ambassadors.

The company is famous for its innovative approach. Employees get free lunches and snacks, Google provides a massage therapist, and a doctor is on-site at the California headquarters.

"Who wouldn't want to work there?" asked Laroche, who was an intern last year and hopes to return full-time.

But the pizza program seems to make Google an even more attractive option, at least among UM students.

"I'm not going to pick where I work just based on who gives me food," said Jaymie Strecker, a computer programming graduate student. But "it gives people a good feeling about them and makes you think about them on a regular basis."