Families with children who have been sexually abused by a parent are being aided by a pilot project in Montgomery County. Suspected cases of incest involving children more than doubled last year, reaching 76 cases in fiscal 1980.

Most child molesters are not strangers lurking by the playground; they are fathers, relatives, friends of the family, according to Linda Canfield Blick, a clinical social worker and director of the Montgomery project. The most common offenders are fathers and stepfathers, and incidents occur in families of all racial and socioeconomic groups, she said.

A young father who has been receiving treatment in a therapy group directed by Blick agreed to tell his story but asked not to be identified. He was interviewed in Blick's presence, and also was identified as a sexual offender under treatment by Robert A. Phillips, who holds a Ph.D. in marriage and family therapy and serves as a consultant to the Montgomery incest counseling project.

"The first time I indulged in any kind of sexual thing with my daughter, she was 2," said the 30-year-old man. During the encounters, he foundled the child and engaged in other forms of sexual activity with her.But, he said, "intercourse was beyond anything I could imagine. Even during the act of sexual play with my daughter, I kept telling myself it was wrong. But i couldn't stop."

The man's wife became suspicious when she saw her daughter acting out sexual behavior with her dolls, and confronted her husband. "I admitted it. I promised not to do it again," he said. And he stopped until they moved to Montgomery County from California 2 1/2 years ago.

The father said he was lonely in a new place and that his relationship with his wife "was zip" because she disliked sex. "I had affairs with other women . . . . I wasn't satisfied."

Again, he said, he turned to his daughter, who was 5. This time the sexual involvement continued for nearly two years befor his wife found out. When she did, the couple turned for help to the Crisis Prevention Center in Montgomery County. The police was informed. "I was scared to death," the man said. I was depressed to the point of trying to commit suicide" by taking an overdose of tranquilizers.

He was convicted of sexual assault and released on condition that he seek treatment from the Montgomery County Department of Social Services project, officially called the Family Assessment and Treatment Program-Child Sexaul Abuse (FATP-CSA), in Rockville. For three months he has attended a weekly therapy group for sex offenders.

The man and his wife are separated and plan to divorce, but he feels the treatment he is receiving has helped him regain self-esteem.

The counselors hope to arrange a meeting soon of the father and daughter, who is now 8. On the few occasions he has seen the child she has been cold and withdrawn. He said he wants to establish a normal father-daughter relationship with his child and, most of all, he does not want her to fear him.

The man's story is a classic example of how and why children are sexaully abuse, according to Linda Blick.

Often parents who sexually abuse their children were themselves molested as children so they abuse is a behavior pattern that is handed from one generation to the next. The father interviewed here said he has vivid memories of being sexually molested by his grandfather, his mother and a cousin.

He said he did not realize the connection between his own abuse as a child and his conduct toward his daughter until he began receiving treatment in Montgomery. Looking back on his childhood, he said, "I've been brought up with the illusion that sex is love."

The fathers and stepfathers who abuse their children usually are insecure men whose marriages are weak and lack intimacy, said Blick. Their sexual expressions of affection are misdirected toward their children, and often begin with fondling and proceed to other types of encounters that eventually may lead to intercourse.

Therapist Phillips points out that adults can be sexually aroused by children. For example a woman who breastfeeds an infant might feel stimpulated, as well as a man who bounces a child in his lap. But, he notes, an emotionally healthy adult will not respond sexually to that stimulation.

Girls are the victims in the majority of cases reported. Psychologists suspect there may be as many boy victims, because they find that about half of the men who seek sexual gratification from their children were abused themselves when they were young.

Specialists say boys often are more reluctant to report the abuse, and older boys may fear being labeled homosexuals. Many adults mistakenly assume that abusers do not violate boys, and thus incidents go unnoticed.

The emotional effects on children -- boys and girls -- can be devastating. Initially, they may be withdrawn and their school work may suffer. Young children may exhibit regressive behavior such as bedwetting, while adolescents may become sexually active, use drugs or run away.

Blick said nearly all teen-aged girls who are sexually abused lose their self-esteem to such a degree that they think about or attempt suicide. She said she knows of at least one successful suicide of a sexually abused teen-aged girl this year in Montgomery County. In rare cases, sexually abused children have developed multiple personalities.

The bulk of the Montgomery incest counseling program's yearly operating budget of $135,000 comes from the Justice Department's Law Enforcement. Assistance Administration (LEAA), which sponsors victim-assistance programs across the country. The program recently received a small grant from the National Center on Child Abuse and Neglect. Both sources of funds may be lost next year, however, of the Reagan administration is successful in pushing through its plans to abolish both the LEAA and the national child abuse center, Blick said.

In Montgomery, proctective-services social workers and police coordinate investigations of all suspected sex-abuse cases and determine the best treatment in each case. Case involving assault by a parent or a child's caretaker are referred to Blick's group. Other cases usually are referred to the sexual assault service at the Crisis Center in Bethesda, which provides short-term counseling, legal and social services.

In Prince George's County, all child sex-abuse cases are handled by the Sexual Assault Center at Prince George's General Hospital, which offers what director Lin Besset terms a "holistic treatment program" that requires each family member to participate in one of the center's therapy groups. A total of 144 suspected cases of child abuse involving both incest and assault by nonfamily members were reported during fiscal 1980.

Experts agree that incidents involving nonfamily members are usually easier to handle because parents are more willing to report a case when it does not involve a relative. Although children may be greatly confused by sexual advances from an adult, they are not likely to feel as betrayed as they would if the offenders were a close relative. In addition, the abuse is not likely to have occurred over a period of time, as is often the case when a family member is the offender.

Sexual abuse often comes to light through accidental discovery by another person, a resulting pregnancy or venereal disease. Most young children will attempt to tell a trusted adult that something has happened to make them uncomfortable, but they often are not taken seriously, says Wanda Thompson, a counselor at the Bethesda assault service.

"We seldom if ever find (physical) proof," said Montgomery County police officer Richard Cage. Abuse may be hard to substantiate; it's the word of an adult against the word of a child. Cage says it is easy to talk to younger children as they play. Adolescents are much more uncomfortable about discussing their bodies.

Prince George's police detective John Warren said instances of abuse that would have been hidden a few years ago are now being reported. But he also believes sexual violation of children is increasing, due to extra stress on families because of economic difficulties.

Both Cage and Warren agree that the number of offenders who go to jail is low, around 2 percent. Most are convicted and are put on probation on condition that they will undergo psychological counseling. When the offender is a family member, Blick asks the court to order that person to stay out of the home and away from the child until therapists determine whether a healthful family relationship can be reestablished.

Mothers of children sexually abuse by fathers have special probelms, says Vicki Siltman, who runs a Montgomery therapy group for mothers. Their reactions are complicated because they often are torn between protecting their children and preserving their relationships with their husbands.

". . . initially (the abuse) is a shock," leaving mothers panic-stricken, Siltman said. Women may feel jealous of their daughters and are forced to decide whether to dissolve their marriages. Through many women decide to divorce others are unwilling to give up the financial security of a marriage -- even a bad one.

Pat is a 35-year-old Montgomery County mother of two daughters, who initially received help from Montgomery social workers. She and her daughter now are being treated by a private therapist. She said her oldest child, now 15, was sexually abused by her father from the time she was 5 until she was 12. When Pat discovered the situation several years ago, she felt shock, like a "kick in the stomach," she recalls. The entire family sought psychological help at Georgetown University Hospital.

But when Pat's daughter enter Junior High school and told a counselor about the incest, police were notified and Pat discovered that the abuse had never stopped.

She confronted her husband, from whom she is now separated. "He denied it right in front of her. I didn't know who to believe," she said angrily.

Pat recalls, "The hurt and hostility in my daughter's eyes told me the truth." Where to Get Help

To report sexual abuse of a child or to request help, call the following numbers:

Montgomery County Department of Social Services' 24-hour hotline, 468-4417.

Community Crisis Center, Sexual Assualt Service, Bethesda, 24-hour hotline, 656-9449.

Prine George's County Sexual Assualt Center (24 hours), 341-4942.

Children's Hospital Center, Washington (24 hours), 745-5000.