Matt Irby hears it all the time as he patrols the cellblocks of the Charles County Detention Center. "I'm old enough to be your father," prisoners tell Irby, who at age 20 is one of the youngest correctional officers in Maryland.

To succeed in a demanding job, Irby needs to keep an even temper, holding in check any fear, contempt or anger as he breaks up fights among prisoners, serves their meals, brings them library books and listens to their grievances and requests.

"This isn't something that most 18- or 19-year-olds have to live with," he said. "It all comes down to respect."

Only in the past year has Maryland allowed correctional officers so young. Last November, the Maryland Police and Correctional Training Commission lowered the minimum hiring age, from 21 to 18, for jobs at the state prison system and in county jails.

The change came in response to complaints from jail officials in largely rural parts of the state who said they were having trouble filling vacancies. Because of the vacancies, officials said, some jails have incurred huge overtime costs.

But so far, the age change has done little to solve the problem.

In Cecil and St. Mary's counties, where calls for reducing the hiring age were loudest, no young correctional officers have been hired. Only two people younger than 21 have sought jobs in St. Mary's, officials said, and no one has applied in Cecil.

"It just doesn't seem to be appealing to 18-year-olds," said Tom Sacks, personnel director in St. Mary's. "We're dealing with people who are more high-tech, who are going on to college. That's what we're up against."

Meanwhile, the commission's decision has worried correctional officials in more populous parts of Maryland who opposed the age change.

"I believe correctional officers need broad life experience, and 18 doesn't cut it," said Arthur Wallenstein, corrections director in Montgomery County.

Wardens at larger jails with few staff vacancies, including those in Montgomery and Prince George's counties, fought against the change and wanted the option of leaving their minimums at 21. This month, however, the Maryland attorney general's office ruled that the change applied to all correctional officer jobs in the state and that all jails would have to give equal consideration to applicants under age 21 or risk being sued for age discrimination.

The director of corrections in Prince George's, Barry L. Stanton, is a member of the training commission and voted for the new policy -- but only because he thought it would be optional, he said. Like some of his colleagues, Stanton said he thinks it is generally a bad idea to put people under age 21 to work in such a dangerous environment, where maturity and sound judgment are important traits for the job.

"I'd like it to return to 21," Stanton said. "The vote was taken at a time when . . . we didn't have all the information to make what I think is a credible decision."

No one under age 21 has yet applied for correctional officer jobs in Montgomery and Prince George's, officials said. It is unclear whether any have applied for jobs in state prisons, but no such applicants have been hired. No one has been hired in Anne Arundel County, either, officials said, although 24 have applied.

At least four people younger than 21 have been hired as correctional officers in Maryland, including Irby, two 19-year-olds in Carroll County and a 19-year-old in Charles. Officials in those counties say the new young officers have performed well.

"They made a believer out of me," said George C. Hardinger, warden of the Carroll County Detention Center.

Hiring teenagers is not unheard of. In Virginia and Pennsylvania and in the federal prison system, correctional facilities can hire at age 18, though they rarely do. In Northern Virginia, almost all correctional facilities hire only applicants who are 21 or older, and federal correctional officers must have a bachelor's degree or three years' experience in management, officials said. In Delaware, the hiring age is 20.

Maryland detention facilities were able to hire 18 year olds until 1982, when questions about maturity led officials to increase the minimum hiring age to 21, said Francis L. Manear, assistant director of the state training commission.

In Charles, 20-year-old Irby has the same responsibilities as other correctional officers, said Walter "Buddy" Poynor, deputy director of the detention center. Irby had been a leader in youth programs run by the county sheriff's office, which made him an ideal candidate for a correctional officer's job even before the policy change, Poynor said.

Some detention centers have started targeting teens for recruitment. The personnel director of the St. Mary's sheriff's office gives presentations to high school seniors. William Jacobs, warden of the Cecil County Detention Center, said he plans to talk with 10th-graders, telling them to stay away from drugs so they can qualify for the job, and its $26,000 salary, when they graduate.

"They're looking for these people to start looking at these jobs as careers," said Stephen Ingley, executive director of the Maryland-based American Jail Association. "The younger you get started into a career, the more likely you are to stay in that career."

Staffing shortages at correctional facilities have been acute in the past decade.

Incarceration rates rose dramatically in the 1990s, and prisons and jails were built faster than officers could be hired, Ingley said. In addition, the booming '90s economy gave young people more employment options, and the low pay and high safety risk of corrections did not attract strong candidates.

Correctional officer unions say that lowering the minimum hiring age is tantamount to lowering standards. Verjeana McCotter, president of the Prince George's Correctional Officers Association, said detention centers should do what some police departments have done in trying to attract more applicants: Increase pay, benefits and training.

"I don't want to see us go backwards," McCotter said.

Despite difficulties attracting young people, corrections officials said they will continuing seeking enthusiastic applicants like Irby, who had long dreamed of a law enforcement career.

"You got to take it on a case-by-case basis," Irby said. "There are 26-year-olds who are not mature enough to do this job."

Correctional officer Matt Irby, 20, talks to an inmate of the Charles County Detention Center in La Plata."It all comes down to respect," Irby says of his dealings with inmates. Irby, here with Sgt. Harry Bowling, had long aspired to a law enforcement career.