Inmates with serious mental illnesses will no longer be locked in cells all day, under new policies outlined Monday by state prison officials.

The change, which follows scathing criticism of the Department of Corrections’ handling of mentally ill inmates, is meant to address one of the toughest tasks in prison management: tailoring discipline to an inmate’s diagnosis.

In 2013, the state’s confinement of 800 to 1,000 mentally ill inmates in Restricted Housing Units — 23 hours per day in small, one-bed cells — was blasted by the U.S. Department of Justice and by advocates for the disabled.

Now the Department of Corrections is putting inmates who might once have gone to “the hole” into new Diversionary Treatment Units.

“We continue to get more and more mentally ill offenders,” said state Secretary of Corrections John Wetzel. America, he said, is “turning our correctional system into a mental health system nationally, and, for the record, that’s a poor policy.”

The upshot, he said: “We have to get better at managing mentally ill offenders.”

Last April, the Virginia-based nonprofit Treatment Advocacy Center reported that the number of seriously mentally ill people in jails and prisons nationally exceeds 350,000 — 10 times the number who are in state psychiatric hospitals.

Some inmates with mental health diagnoses contend that prison policies are making them worse.

Richard Dale Thomas, 29, of Vanderbilt, Fayette County, suffers from bipolar disorder, he wrote to the Pittsburgh Post-Gazette. He’s at the State Correctional Institution Greene because he was found guilty of harassment following burglary convictions.

Guards alleged that he defied them by sitting during morning inmate count, he wrote. Resulting disputes landed him in the Restricted Housing Unit since May 31. His symptoms have dramatically worsened, he and his family claimed.

He wrote that corrections officers covering “the hole” needle mentally ill prisoners, prompting some of them to snap and generating more discipline. “Do you think society would like hundreds of lions brought into this evil compound and poked with a stick every day for years, then set [loose] into society?” he wrote.

About 24 percent of the state’s 49,062 inmates are getting psychological or psychiatric treatment, according to Dr. Robert Marsh, director of psychology for the Department of Corrections. About 4,000 inmates are characterized as having serious mental illnesses.

Discipline is one of the thorniest issues. The Harrisburg-based Disability Rights Network in a 2013 lawsuit against Mr. Wetzel called the system “a Dickensian nightmare, in which many prisoners, because of their mental illness, are trapped in an endless cycle of isolation and punishment,” sometimes ending in suicide.

Dr. Marsh said that system is changing. When a seriously mentally ill inmate faces discipline, he now gets a psychological examination. That will often result in assignment to a new Diversionary Treatment Unit, rather than a Restricted Housing Unit.

In diversionary treatment, inmates see art and recovery-related messages, rather than stark walls, Dr. Marsh said. They get a minimum of 20 hours per week outside the cell, versus five hours in restrictive housing. The inmate is asked to help to craft, and then participate in, a treatment plan, he said.

“We need to achieve that goal of closer supervision and see that as an opportunity to hopefully improve their mental state,” Mr. Wetzel said, “or at least not push their mental state in a bad direction as a result of the sanction.”

Last year, the Department of Justice reported that the state was reducing the use of solitary confinement for mentally ill prisoners.

On Wednesday, attorneys for the state and the Disability Rights Network told a federal judge that a settlement of their lawsuit “is imminent and the agreement should be executed within the next few weeks.” The settlement is expected to commit the state to detailed overhauls.

Other states have settled similar lawsuits, said Henry Dlugacz, a New York City-based attorney and a psychiatric social worker who serves as an independent monitor for such pacts. “The implementation is the biggest part of the battle, but you can’t do that without having the right template.

“You need the personnel, the funding and the sustained interdisciplinary commitment to carry it out,” he said.

SCI Cresson, where seriously mentally ill inmates were kept in Restricted Housing Units for months or years, closed in May 2013. Its many mentally ill inmates were dispersed to 14 prisons.

The SCI Pittsburgh now houses about 200 inmates with mental illnesses, and SCI Greene, in Waynesburg, can handle 250.

SCI Greene inmate Joel Robert Snider, 37, of St. Louis is serving a 20- to 40-year sentence for third-degree murder after pleading guilty by reason of mental illness. In letters, he complained of arbitrary medication changes, harassment by corrections officers, removal or destruction of religious items and time in “the hole.”

In May 2013, he sued scores of state officials and employees, alleging harassment. On Wednesday, he filed a motion asking a judge to order the department to provide the psychiatric medicines Geodon and Effexor consistently.

Mr. Wetzel acknowledged that SCI Greene is an odd setting for mental health treatment. “It was designed to be Pennsylvania’s version of a supermax,” he said, with an emphasis on security.

Dr. Marsh said one pod in Greene’s Restricted Housing Unit has been converted to a Diversionary Treatment Unit.

He added that all prison staff will be trained by March in “mental health first aid” and many others are getting a 32-hour course in preventing psychological crises.

That costs money, Mr. Dlugacz said, but inaction costs more.

“What’s the cost when someone gets out and is not prepared to be a productive member of society and can’t be a mother or father?” he asked. “What’s the cost of someone who [leaves prison and] commits another crime?”

First Published: January 6, 2015, 5:00 a.m.