On the living room wall of an otherwise nondescript Rockville home, a poster lists the house rules, including required chores, permitted hours for TV viewing and the curfew time. A sign-out sheet is taped to the refrigerator.

This is Stepping Stones Shelter, which offers food, housing, counseling and a philosophy of self-help for men, women and children in need. For security reasons, because some of the residents have fled from tense or violent situations, the shelter's address is confidential. People can reach it through P.O. Box 712 in Rockville, Zip Code 20851.

Next month, the shelter will move to larger quarters to meet the growing demands of the homeless, most of whom are from Montgomery County.

Last year, the shelter counted 123 overnight residents. Since opening in 1980, it has housed an average of four to five people a night, most for a fortnight, all without charge.

In the kitchen, Nancy, 20, feeds her year-old twins. They have lived in the four-bedroom home for three weeks and are about to move to an apartment of their own.

"As soon as I move out, I'll come back as a volunteer," she says. "If I didn't have the shelter I'd be in trouble."

Nancy says she and her children were forced out of their house by her mother's boyfriend. " The shelter is providing milk and diapers for my boys. They found a specialist for my son who's having ear trouble," she says.

"I'm going to help with the move to the new house," Nancy adds. She looks forward to being self-sufficient and returning to her job as a pharmacist's assistant in Gaithersburg.

She might be considered a success story among Montgomery County's homeless. According to the Montgomery Department of Social Services, there were 474 cases of homeless people who sought help from county agencies in the past year.

Helayne Baker, who radiates enthusiasm, is the shelter's director. She often puts in 12-hour days, acting as a mediator in family disputes and coordinating help from other social service agencies. After telling a caller there is no vacancy, she describes the shelter's coming move. Stepping Stones will take over a 20-room historic Rockville farmhouse that can accommodate as many as 20 people at a time. Currently, more than half the calls it receives must be referred elsewhere for lack of space.

"It will triple our capacity," Baker says. "We'll expand the staff and have yearly fund-raisers" to meet the mortgage payments. Currently, she is the only paid staff member. Most of the shelter's funds come from religious organizations and government block grants.

"The majority of those we see are not abused or battered women. We see a lot of people with family conflicts; people who've been evicted, lost jobs and subsequently lost their homes," Baker said. "Most are what we consider temporarily displaced persons. We try to stop the problem before it becomes a chronic situation."

Baker is described in glowing terms by those who have benefited from their stay. "Helayne helped me get food stamps. And we found an apartment, thanks to Helayne," Nancy says, picking up crackers dropped by her twins.

The atmosphere in the shelter is distinctly noninstitutional.

The night's cooking rotation falls to Dave, who happens to have a special recipe for spaghetti sauce. A meal schedule dictates the menu; household rules stipulate dinner is to be eaten between 6:30 and 8. At the stove, Dave, who is in his 40s, says there are more rules here than at the shelter where he lived previously, "but I'm able to cope." He says he held a job until two years ago when he suffered a back injury.

"I just started going downhill. I wish I were younger so I could go back in the service. Once you've been down," he says, "it's hard getting back."

Baker says the shelter accepts anyone, "provided they are not on drugs and don't have drinking or severe emotional problems."

Initially, people are admitted for 24 hours. After an appraisal, they are given three days to determine if the shelter meets their needs, while Baker decides whether they are suitable residents. "If they come in drunk even once, they're out," she says. Then a 14-day stay is arranged, although the limit is flexible if a resident is working at finding a job or permanent living quarters.

Every Wednesday, the shelter holds a meeting of residents and volunteer interns to discuss problems and goals. Each evening, before the 11 o'clock curfew, residents fill out a "plan of action."

An anonymous example:

"Today, checking into housing, meeting with Helayne in a.m. P.O. probation officer may stop by. If not, I'm to call her Thursday after get to job. Prepare for work Thursday. Try to get to AA meeting."

Baker says the homey atmosphere is important, but "when people get too comfortable here, we shake 'em up a little bit.

"They're used to living in their own home or apartment. We try to give them every bit of dignity and self-respect they deserve."