By ANNA PRIOR

In Brookfield, Wis., no restaurant has triggered more calls to the police department since last year than Chuck E. Cheese's.

Officers have been called to break up 12 fights, some of them physical, at the child-oriented pizza parlor since January 2007. The biggest melee broke out in April, when an uninvited adult disrupted a child's birthday party. Seven officers arrived and found as many as 40 people knocking over chairs and yelling in front of the restaurant's music stage, where a robotic singing chicken and the chain's namesake mouse perform.

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Chuck E. Cheese's

Chuck E. Cheese's bills itself as a place "where a kid can be a kid." But to law-enforcement officials across the country, it has a more particular distinction: the scene of a surprising amount of disorderly conduct and battery among grown-ups.

"The biggest problem is you have a bunch of adults acting like juveniles," says Town of Brookfield Police Capt. Timothy Imler. "There's a biker bar down the street, and we rarely get calls there."

It isn't clear exactly how often fights break out at Chuck E. Cheese's 538 locations. Richard Huston, executive vice president of marketing for the chain's parent company, CEC Entertainment Inc. of Irving, Texas, describes their occurrence as "atypical," saying he has heard of "four or five significant adult altercations" this year. But in some cities, law-enforcement officials say the number of disruptions at their local outlet is far higher than at nearby restaurants, and even many bars. "We've had some unfortunate and unusual altercations between adults at these locations," Mr. Huston says. "Even one is just way too many."

Fights among guests are an issue for all restaurants, but security experts say they pose a particular problem for Chuck E. Cheese's, since it is designed to be a haven for children. Law-enforcement officials say alcohol, loud noise, thick crowds and the high emotions of children's birthday parties make the restaurants more prone to disputes than other family entertainment venues.

The environment also brings out what security experts call the "mama-bear instinct." A Chuck E. Cheese's can take on some of the dynamics of the animal kingdom, where beasts rush to protect their young when they sense a threat.

Stepping in when a parent perceives that a child is being threatened "is part of protective parenting," says Frank Farley, a psychologist at Temple University and former president of the American Psychological Association. "It is part of the species -- all species, in fact -- in the animal kingdom," he says. "We do it all of the time."

Now some towns are asking CEC to step into the ring. Amid pressure from local politicians, some Chuck E. Cheese's have stopped serving alcohol and added security guards who carry pistols.

CEC has been tightening safety rules to deter fighting in other ways. In Milwaukee, the store posted a sign outlining a dress code that prohibits what it calls "gang-style apparel." That location also implemented a code of conduct that prohibits knives, chains, screwdrivers and glass cutters. CEC is considering systemwide signs at popular games such a machine that draws digital pictures of customers to let people know there may be a time or token limit. Making the machines more expensive to use is another option, but Mr. Huston says that is "inconsistent with our value message."

In Pennsylvania, Susquehanna Township police are searching for suspects involved in a Nov. 9 altercation at a Chuck E. Cheese's outside Harrisburg. The police department gets called to respond to disputes at the restaurant as many as 15 times a year, Police Chief Robert Martin says.

This most recent assault, described in police reports, occurred after a woman in her 30s approached a 6-year-old boy who was playing a videogame. When the boy went to insert more tokens to continue playing, the woman grabbed the tokens out of his hand and told him to stop hogging the game. The boy went and got his 26-year-old mother, who walked over to the woman. The woman began screaming at the boy's mother, and another suspect, a man in his 30s, grabbed the mother by the throat and pushed her against the videogame machine. CEC employees had to pull the man off the mother. Both the man and the woman fled the scene.

In Toledo, Ohio, four women were charged with disorderly conduct after a melee erupted at a Chuck E. Cheese's there last year. According to police reports, it started when parents complained to the restaurant manager that children were loitering at the drawing machine. The children were Barbie Clifton's daughters, then 14 and 10 years old. Ms. Clifton had come out of the bathroom when she saw a woman yelling at her daughters and her friend.

"I thought, 'Oh my God, what's happening here?'" says the 42-year-old stay-at-home mom. "Instead of [the woman] going to the parent or going to the manager, she was calling my friend and daughters all of those names."

That touched off a fight between more than 10 people, in which participants punched and screamed at each other. One woman removed the red rope that marks the entrance queue and handed it to another woman, who swung the metal clip attached to it at others involved in the incident.

"I thought they were going to start attacking me," says Sheri Kellar-Raab, the first officer who responded.

CEC's Mr. Huston says the company is working to deter these types of incidents. "It's critically important for us to provide a safe, wholesome environment for the parents and the kids," he says. "This is not what we're all about."

Reginold Bell, a 45-year-old Milwaukee social worker, says that a child "assaulted" his 8-year-old son at a local Chuck E. Cheese's while the boy was playing in the Sky Tubes, a jungle gym with slides. Mr. Bell confronted the man who appeared to be the child's father, setting off an argument in which the man "used some vulgar vernacular," says Mr. Bell, who reported the incident to the police department.

"I was really angry, but I've got my kids here, so I kind of backed away," Mr. Bell says. A manager asked the two men to sit down and talk out their differences, he says. They didn't.

The first Chuck E. Cheese's was opened in San Jose, Calif., in 1977 by Nolan Bushnell, founder of the Atari videogame company. He thought there weren't enough places where young people could play games in a family atmosphere, according to a company history.

To appeal to adults, about 70% of the chain's locations serve wine and beer. Some city officials have pinpointed that as the main cause of the fighting. Milwaukee Alderman Tony Zielinski called for the removal of Chuck E. Cheese's beer-and-wine license in 2006 after he received police notification and complaints from constituents about fighting there. The company stationed armed security guards inside the restaurant in an effort to make it safer.

"It was like something out of a Quentin Tarantino film," says Mr. Zielinski, referring to the "Pulp Fiction" director. "What parent is going to take their kids to a place where there is alcohol and pistols being brandished?"

CEC's Mr. Huston said the armed guards were installed after the Milwaukee Police Department suggested bolstering security at the restaurant; a police department spokeswoman said the department didn't recommend armed security.

Police officers and company officials say alcohol isn't always a factor in altercations at Chuck E. Cheese's. Mr. Huston says the chain's "broad demographic appeal" means that it has restaurants in what he described as "tougher areas" where there is more potential for crime.

Mr. Zielinski held a news conference in front of the restaurant in late 2006 and threatened to push for the removal of the location's arcade and gaming license. Shortly after that, CEC gave up the restaurant's beer-and-wine permit. Mr. Huston says the company did stop serving alcohol to reduce fighting but not because of pressure from Mr. Zielinski. CEC also took alcohol off the menu at a Chuck E. Cheese's in Flint, Mich., in February, a month after police responded to a fight there involving as many as 80 people.

Chuck E. Cheese's Milwaukee location has generated substantially fewer calls to the police department since it introduced its rules about dress and contraband items last year. In Brookfield, police haven't received reports of altercations at Chuck E. Cheese's since it gave up its alcohol license at the end of June, implemented codes of dress and conduct and tightened parking-lot security.

Write to Anna Prior at anna.prior@wsj.com