As dusk falls on a recent Monday evening, Montgomery County's mobile crisis team hits the road, winding through the remnants of rush hour traffic to try to help a mentally ill man who seemed capable of violence in previous encounters with county workers.

Someone at a nonprofit organization, located in a house in Gaithersburg, has called in the crisis team, worried that the man might act out. He has appeared to be hallucinating or hearing voices. He doesn't speak English.

Social worker Jim Gilmore is at the wheel of a white county-owned SUV. In the passenger seat sits Beth Tabachnick, also a social worker, who is on the phone with a family member of the mentally ill man. She is learning all she can about his recent condition before she and Gilmore intervene.

They travel light: a couple of cell phones, a procedural handbook, a police radio.

Gilmore pulls into the driveway of the house, turns the car off and uses the radio to call for a police officer to assist in the intervention. As a half-moon rises on the horizon, he and Tabachnick wait in their darkened vehicle for the officer to arrive.

The two social workers are staff members of the county's Crisis Center, Montgomery's round-the-clock service for the mentally ill and others in crisis, such as those dealing with the loss of a loved one, victims of abuse and the homeless.

County leaders and mental health care advocates have wrestled for years with how to improve long-term services for the mentally ill, but they agree that the Crisis Center is effective in responding to the immediate needs of the county's most vulnerable residents.

"They do good work," said Kevin P. Dwyer, a retired school psychiatrist who two years ago chaired a county task force on mental health. "They care about what they do."

Dwyer's panel found that the county's system for delivering publicly funded mental health services was "in collapse, crippled by severe state under-funding, and lacking any coherent structure or plan to maintain accountability and ensure a humane safety net for the county's most vulnerable children and adults."

Although county officials have since developed plans to improve the system, Dwyer says now that "there's no concrete evidence that they're implementing a comprehensive plan."

In the late 1990s, the county privatized most of its mental health clinics, in large part because the state began directly reimbursing mental health professionals for services to the poor rather than supporting locally run clinics.

Council member George L. Leventhal (D-At Large), who chairs the council's health and human services committee, acknowledges that there are unmet needs. "We at the local level are paying for an abrogation of responsibility at the federal and state levels," he said.

This year, he said, the county is expanding services at one of its two remaining clinics. The move is an acknowledgment that -- as mental health advocates say -- the state's fee-for-services system is not meeting the needs. Some of the privatized clinics have closed because of financial problems.

Montgomery's commitment to mental health care seems to lag behind ambitious plans, under review by county leaders, to offer primary care to every resident within several years. "We have a better story to tell on primary care than on mental health," Leventhal said, "but I'm not going to agree that primary care is a higher priority."

But Dudley E. Warner, senior administrator of the county's Behavioral Health and Crisis Services, said the Crisis Center offers proof of a sort that the mental health system is functioning. "If you had a totally dysfunctional system, the Crisis Center would be overrun, and that's not the case here," he said.

After the officer reaches the Gaithersburg house, Gilmore and Tabachnick, standing in the driveway, give him a brief rundown of the situation. Then they go in.

Gilmore and Tabachnick have a word with the person who called the Crisis Center about the man's condition. The man is in a room at the rear of the house watching television. The officer stands ready and says little.

Gilmore gently invites the man to sit near a telephone. Then Gilmore calls a translation service contracted by the county and turns on the speakerphone. An interpreter begins translating Gilmore's questions, and the man answers calmly. (County officials allowed a reporter to witness the Crisis Center's work and accompany its mobile team on the condition that identifying details about clients not be revealed.)

As the interview proceeds, the level of anxiety in the house subsides. Gilmore asks the man whether he feels safe. "I feel that I am at peace, that I am safe," the man says. He knows it is Monday, where he lives, that he has a doctor's appointment the next day. After about 20 minutes, the officer, now joined by a colleague, leaves.

Reassured, Gilmore ends the interview. The man wants to know whether his family has Gilmore's phone number. Gilmore thanks him for his patience and cooperation. The person who called in the crisis team seems relieved. The intervention takes half an hour.

Back at the center, Gilmore reflects on a smooth experience. "That's the way it's supposed to go," he says.

County officials created the Crisis Center a quarter-century ago to help teenagers with drug problems. "That never evolved," says Thomas E. Harr, a former county health official who is now executive director of the Family Services Agency Inc., a nonprofit social service organization in Gaithersburg. "But other people in crisis started to use it." Today the bulk of the center's clients are the mentally ill.

The center's 45 staff members -- including three psychiatrists and three dozen social workers, counselors and psychologists -- handle as many as 55,000 calls and 6,500 walk-in clients a year. Its budget for the fiscal year that ended in June was $3.9 million.

Mobile crisis teams can be deployed from 8 a.m. to midnight when situations demand on-site intervention. The center also sends therapists and volunteer mental health professionals to counsel residents after disasters or major acts of violence. The center worked with Montgomery's Mental Health Association to create the volunteer network.

During the sniper attacks in October 2002, the center received 7,000 calls in three weeks -- more than double the average -- and activated the network for the first time.

The center provides the county's frontline response to homelessness, referring those in need to shelters, and maintains seven beds to accommodate mentally ill clients for a period of up to three days while they are evaluated by staff members.

The center's "assertive community treatment" team keeps in touch with chronically ill patients who are without resources and have not responded well to traditional treatment. The team's caseload is about 70 people.

After several national calamities -- the 1999 Columbine High School shootings; the events of Sept. 11, 2001; the sniper attacks -- Warner said that "it's clearer to people how important it is to address the emotional impact of these things."

Situated in the ground floor of a county building on Piccard Drive, the Crisis Center consists of a call center with about a dozen cubicles, a wing of dormitory-style bedrooms with a lounge, and interview rooms for therapists and clients.

The call center looks as if it might host a small telemarketing firm, but for a television screen displaying images from cameras in one of the interview rooms, the lounge and other parts of the center. A billboard displays the number to call in the event of a spill of bodily fluids. A bin contains prescription drugs waiting for clients to pick up.

After Gilmore and Tabachnick return, a mother brings in her grown son, who is mentally ill and has been behaving erratically. Social worker Judy Shuck admits him so doctors can stabilize his medication.

Other therapists take the steady flow of calls. A victim of a crime calls because she is afraid to remain at home. A father calls to say his ex-wife is abusing their children. A child calls to say her mother is beating her.

One by one, these and other situations are resolved, at least temporarily. Some people are referred to other county agencies or to nonprofit organizations that might help them. Some callers are told there is nothing the county can do for them.

The therapists subsist on coffee, pizza and their good humor. Shuck has worked in the center since 1996, counseling people at all hours of the day and night. "I couldn't imagine working anyplace else," she says.

The Montgomery County Crisis Center is at 1301 Piccard Dr., near the intersection of West Gude Drive. The number is 240-777-4000. The center and its crisis line are open 24 hours a day, seven days a week. The center is accessible from the following Ride On bus routes: 63, 45, 66 and 54.

Therapist Mike Schappell, above, talks with Pam Rossomondo, an administrative assistant at the Crisis Center's walk-up window in Rockville. Below, nurse Eva Stolwein checks medical supplies. Police officers listen to Rhona Sollod of the National Alliance for the Mentally Ill during a crisis intervention training session. The Crisis Center was created to help teenagers with drug problems, but now it mostly serves the mentally ill, the homeless and others.Nurse Eva Stolwein is among the Crisis Center's 45 staff members, who include psychiatrists, social workers, counselors and psychologists.