The roots of one of the national youth problems unfamiliar to most Americans - teen-age prostitution - often lead back to the family.
And the families are not just ones with single parents or low incomes. The issue cuts across economic and social lines, according to research on the topic.
But, according to experts on the issue, there are practical steps that parents, schools, and others can take to reduce the likelihood of a conflict so severe that it might induce a youth to run from home - a flight that can lead to involvement in a number of crimes, including prostitution, drugs, and theft.
One way to get a better understanding of just what steps can be taken - by families and community organizations - is to understand the teen-age prostitute better: who he or she is, why they apparently got involved in the activity, and how they are being helped out of it.
A study by a California research organization, soon to be released by the federal government, provides a profile of male teen-age prostitutes. The study, by Urban and Rural Systems Associates of San Francisco, is based on several months of interviews with teen-age prostitutes in San Francisco and New York and questionnaire data filled out by 79 male teen-age prostitutes.
Among other things, the study found: About half the males said they were homosexual or bisexual; most were 16 or older; more than a third said they had been the victim of some physcial, emotional, or sexual abuse at home.
Most of the male youths who identified themselves as homosexual said they were not getting help from social service agencies. Some said they were reluctant to seek such help, for fear of being rejected.
Few runaway homes or other agencies have personnel trained in dealing with male or female prostitutes or with males identifying themselves as homosexuals.
While male teen-age prostitutes generally operate on their own, most female prostitutes, including teen-agers, the study shows, operate under the control of a pimp. A pimp is a man who generally provides for their lodging, food, and clothes but who also takes their earnings - and may physically abuse them if they do not provide enough money.
Helping teen-age girls stay away from prostitution is often ''a battle (with the pimp) of who can win the trust and confidence'' of the girl, Ruth G. Richardson, director of Three Rivers Youth home for girls in Pittsburgh told a congressional panel earlier this year.
In Denver, Sharon Bryant is trying to win that battle to help some of the local teen-age female prostitutes. In March, she opened a home where up to nine teen-age girls can live while adjusting their lives.
One girl being helped by the Denver Chrysalis Project quit school and ran away from home at 13 after being the victim of incest. Through a friend, she met three pimps, who ''held her down, shot her up with dope,'' and put her on the street as a prostitute, Ms. Bryant says. But she was arrested and referred to Chrysalis by a social worker.
Today the girl is ''doing great,'' is back in school, and is pressing charges against the three pimps, Ms. Bryant says.
Seattle and Boston are also opening a small number of residential units for teen-age prostitutes who want to quit that life and make a new start. In Seattle , The Shelter has been in contact with about 700 teen-age prostitutes in the past nine months, says a staff member, Brother John Savage.
But such facilities are rare across the United States.
And even police say legal efforts alone are not the answer. Prosecutions of pimps are complicated by the need for witnesses, and seldom do the girls involved offer to testify, either out of fear or because of emotional ties to the pimp.
Parents, schools, and communities can help, however, according to experts. Among their suggestions:
* Parents should talk openly with their sons concerning feelings about homosexuality. If a boy is not encouraged to discuss such feelings, he may hide them at home but explore them through illicit activities on the street.
* Parents should ''listen to their kids - really make the kids feel you care, '' suggests Barbara Whelan, director of a youth program in Boston that helps teen-age prostitutes, among others. Once they run, it is often too late, because about a fourth do not go back and may get involved in street crime, including prostitution, she says.
* Schools should start courses in family communications, and communities should do more to help youths find jobs.
* Homes for runaways should be supported and others opened; counseling and residential programs should be expanded - programs aimed at helping teen-age prostitutes and teen-agers who say they are homosexual.