Outcast teens find sanctuary in Bronx home; Widening Circles, by Elizabeth Lyttleton Sturz. New York: Harper & Row. 334 pp. $15.95.

They are the throwaways, young people nobody else wants. They come to Argus Community, amid the ashes of the South Bronx, numbed by incredible emotional, physical, and sexual abuse, their spirits fragmented and broken.

Few know the meaning of the words ''home'' or ''family.'' Many have turned to self-destructive behavior - drugs, attempted suicide. Many are violent. They try to appear tough, while inside they are dying, certain they can never make a life for themselves.

People and agencies that try to help often despair and turn them away - but not Elizabeth Lyttleton Sturz. She takes them into Argus. And with her simple philosophy - that given a safe environment in which adults demonstrate the ''power of a loving community,'' young people will respond in kind - she succeeds where others fail.

''Widening Circles'' documents the founding, in 1968, of the Argus Learning for Living Center. Today, some 300 troubled adolescents each year - about half of them black, the other half Hispanic - are cared for in its drop-in treatment center or its residential home for those with no suitable place to live.

Ms. Sturz traces Argus's roots to her volunteer work in antipoverty and probation programs, her faith that no child is ever lost, and her search for an ever-widening circle of personal growth. Her belief: Change behavior instead of probing causes or attaching labels.

She has contributed some unique components to the Argus structure. Adult counselors are drawn from the Bronx neighborhood; many have overcome the same traumas their teen-age charges face. The teen-agers soon learn to look after each other, love each other, pressure each other in peer groups to forsake negative influences for the positive.

A ''no physical violence'' pact forbids weapons on the premises; staff members may not resort to physical punishment, even under the most extreme provocation. Hugs, kindness, a sense of order, strictly enforced rules, and courtesy win the day. When young people ''discover they are lovable,'' Ms. Sturz says, they learn to take responsibility for their own lives.

The story is told in case studies of the Argus extended family of adolescents and the adults who work with them. The cases read like short stories, except the tragic and often shocking histories are true.

Ms. Sturz has an ear for dialogue and the ability to make people come alive. She is scrupulously honest and spares no one, including herself. Failures are documented as well as successes. The reader is snared, rejoicing with the author when battles are won and a child forsakes drugs, gets a job, goes to college. She writes:

''When I learn . . . a girl's suicide attempts have ceased; when these kids share their experiences, dreams, aspirations, I am transported. When a kid tells me she regularly visits the Frick and the Metropolitan (never having been out of the South Bronx before coming to Argus), I am elated.''

Her admonition: ''Saint Augustine saw the nature of God as a circle whose center is everywhere and whose circumference is nowhere. Our highest (and our most earthly) task is to find our own center and to go out from it, with God if you like, but always with our fellow creatures and toward that bondedness which is the full expression of our humanity.''

This is not an easy book to read; it tugs at the heart and conscience. There are hundreds of thousands of children like those in ''Widening Circles'' who do not have an Argus home to turn to. They are crying, and we must listen.

The grand thing Ms. Sturz contributes is hope and the willingness to share the Argus program through a teaching program for those who wish to emulate it. Best of all, she proves even the most troubled young person can be helped with loving care.