When Pennsylvania casinos open to receive thousands upon thousands of slot machine players, state regulators hope to minimize compulsive gambling with the help of one special group: the gamblers themselves.

Pennsylvania will become the latest legalized-casino state to adopt a "self-exclusion" program. It encourages admitted problem gamblers to volunteer to be denied access to the casino floor, to be denied winnings if they sneak in, and to be thrown out -- and possibly arrested for trespassing -- if they're caught.

The Pennsylvania Gaming Control Board announced last week that compulsive gamblers wanting protection from their addiction can begin showing up at its office in Harrisburg to fill out an application and be photographed.

They will end up on a computerized list to be shared by all of Pennsylvania's future 14 casinos, said Nanette Horner, the gaming board's director of compulsive and problem gaming enforcement. Once each slots operation is up and running, individuals also will be able to sign up for the program at those locations.

"The Legislature, the gaming control board and the gaming industry realize the need to take responsible measures to assist people who have compulsive-gambling and problem-gambling issues," Ms. Horner said. "Frequently, the person who is in the best position to seek assistance to control the problem is the person afflicted."

Missouri, Iowa, Michigan, Illinois, Indiana, Arizona, Mississippi, Louisiana and New Jersey are among states that already have such programs, with lists that range in size from hundreds to several thousand or more. The rules pertaining to the lists also differ in each state.

Advocates for control of problem gambling note various flaws with the programs, particularly the enforcement difficulty in spotting those who ignore the self-prohibition after signing up. But they and other analysts within and outside the gambling industry view the self-exclusion lists as better than nothing in terms of helping those who have trouble helping themselves.

Estimates of the compulsive gambling population vary, but it has been cited frequently that about 1 percent of adults are pathological, and another 2 percent to 4 percent have problems that border on that and also might benefit from self-exclusion -- at least temporarily. People in Pennsylvania, as in many states and casinos such as Harrah's that maintain such lists themselves, may opt to be banned for one year, five years or a lifetime.

"Exclusion lists are not the silver bullet to the problem," because compulsive gambling is a matter of impulse control and people often work to get around whatever barriers are put in their way, said Tim Christianson, president of the Association of Program Gambling Service Administrators, made up of officials from various states.

"But if you marry that with support groups and individual counseling, it can be very effective," added Mr. Christianson, treatment administrator for the office of problem gambling in Arizona.

Most states that have gambling dedicate a portion of revenue derived from gaming to education, research and treatment programs of some kind to address problem gambling; Pennsylvania has established a minimum $1.5 million annual fund for that purpose.

Legislative proposals in recent weeks to raise that amount to $4 million failed to be enacted. Pennsylvania Department of Health officials are developing the guidelines for how that $1.5 million will be spent.

Missouri's is the most extensive of the exclusion programs with more than 10,000 names. Melissa Stephens of the Missouri Gaming Commission said that could be both because it is the oldest -- from 1996 -- and because there is only a lifetime ban and no one is ever removed.

Ms. Stephens said the state is moving toward a program like Pennsylvania's and other states, with shorter-term options.

"A permanent lifetime self-exclusion with no possibility for removal is a very intimidating step for an addict to take," Ms. Stephens said. "Individuals who are afraid of developing problems during a high-stress period, they would like to be on the list for a limited period of time. There have been studies that support that as a beneficial step."

Other differences in Missouri from most states are a carding system for everyone entering a casino and mandatory arrest of violators for trespassing. Arrests will be possible, but not mandatory, in Pennsylvania.

Missouri's carding system is part of a technology that makes sure people don't exceed state limits of $500 in losses every two hours, another control not adopted in Pennsylvania or most other states.

Pennsylvania casinos will rely in part on facial identity familiarity for casino staff to recognize those on the list, but other safeguards will apply, such as catching people if they try to cash a check. In Pennsylvania, as in many states, any winnings a violator is found with will be forfeited to the state's problem gambling treatment fund.

Much of the work in enforcing the ban will be up to the casinos themselves, and they also are required to file independent descriptions with the state gaming board of their own plans to address problem gambling. They will be expected to advertise information about how patrons should seek help if their gambling is out of control, Ms. Horner said, though there is no specific state standard for how they are to do that.

Harrah's, the world's largest casino company, often is credited with being the industry leader in raising awareness of problem gambling by advertising and other means, and is a believer in the usefulness of the bans, said Jennifer Shatley, the Harrah's Casino vice president overseeing problem gambling.

Shared among all of its properties, Harrah's maintains its own list of about 40,000 patrons who indicated they want to receive no promotional material, comp offers or credit from the company. Many of those also sign up to be banned, and the company interprets that to mean keeping them off of its properties entirely, even away from restaurants and entertainment venues, although Pennsylvania's exclusion only applies to the gaming floor.

With so many people coming into casinos, Ms. Shatley said, the ultimate responsibility for compliance lies with the gamblers themselves.

"We're required to identify them to our best faith," she said, but many will slip through until they attempt a transaction that requires identification, such as cashing a check or obtaining a jackpot that must be recorded for tax purposes.

More information on the application process for the self-exclusion program is available on the state board's Web site, www.pgcb.state.pa.us.