The story is so haunting it's almost hard to believe. Amy Biehl, an idealistic California college student, wins a Fulbright Scholarship to travel to South Africa to assist the anti-apartheid movement; she goes there, and is murdered by a black mob during a riot. After years of grief, her parents Linda and Peter quit their trendy upper-middle-class California jobs and move to South Africa to try to complete the work their daughter started.

Eventually Amy's parents meet two of their daughter's killers, who are now full of remorse. The two young men, who have been pardoned, try to atone for their crime by doing public service for a foundation the Biehls established in Amy's name. Amy's parents forgive the two killers and they become friends, so much so that the young men address Amy's mother as "mom."

Hard to fathom? Few among us could be so forgiving, despite what religions teach. Amy Biehl must have been an exceptional person to inspire her parents to transform their lives in her memory. Her parents must be exceptional as well, to be capable of such acts. But exceptional though they are, their experience is an unusually dramatic example of a rule that applies to everyone: that forgiveness is good not just for the person who is forgiven, but also for the person who forgives.

Traditionally, we think of forgiveness as a blessing extended to the transgressor, easing his or her conscience; the person who does the forgiving is seen as engaged in a gallant self-sacrifice. In this traditional view, the forgiven person benefits while the forgiver gains nothing. But what if forgiveness is just as important for the person who forgives as for the person forgiven? What if it's in your self-interest to forgive, because you will be better off?

Consider that once the murder happened, Amy Biehl was gone: nothing could bring her back. Her parents might have allowed their lives to be burned up in hatred for the people who committed the crime and for the place where it happened. Instead, they forgave. The sorrow of their loss will never go away. But otherwise, forgiving Amy's killers left the Biehls better off.

Today, rather than having their lives subsumed in bitterness, Amy's parents are leading important, constructive lives as part of the great South African reconciliation effort. They keep Amy's spirit alive as a living memory, and they feel hope rather than anger. Strictly from the standpoint of their own self-interest, the Biehls are better off than if they had refused to forgive.

A one-of-a-kind situation? Hardly. Increasingly, psychological research has begun to show that being a forgiving person is essential to happiness. Even when someone wrongs you, feeling anger or hatred only causes your life to descend into misery and resentment: You are the one who suffers, not the person you're angry at. Forgiving, on the other hand, can lift the burden. When Buddha and Jesus and other great spiritual figures taught us to forgive those who sin against us, they weren't just pronouncing holy philosophy. Rather, they were giving practical down-to-earth life advice.

In his book, "The Forgiving Self," clinical psychologist Robert Karen describes case histories of patients whose lives have benefited by forgiving, and offers practical advice on how to bring yourself to forgive. Similar insights come from another clinical psychologist, Everett Worthington, Jr., author of "Five Steps to Forgiveness: The Art and Science of Forgiving."

Worthington, who is a professor at Virginia Commonwealth University and a pioneer in forgiveness research, has found that people who won't forgive the wrongs committed against them tend to have negative indicators of health and well-being: more stress-related disorders, lower immune-system function, and worse rates of cardiovascular disease than the population as a whole. In effect, by failing to forgive they punish themselves. Unforgiving people are also thought to experience higher rates of divorce, which also reduces well-being, given that married men and women consistently do better on most health barometers, including longevity.

In contrast people who forgive, Worthington finds, may have better health, fewer episodes of clinical depression, longer marriages and better "social support," another indicator of well-being. This latter means forgiving people get along better with others, who in turn come to their aid in social-support situations.

Forgiveness research is a comparatively new field. Psychologist Kenneth Pargament of Bowling Green University says that while psychology has long studied the coping mechanisms that people use to deal with anger, resentment, and desire for revenge when they are wronged, only recently has forgiveness--in some cases, the ultimate form of coping--become a common subject of research.

Some of the reluctance to study forgiveness stems, Pargament supposes, from the assumption that forgiveness can only be motivated by faith. A study at the University of Maryland found that many psychotherapists would discuss forgiveness with patients only or mainly in a religious context.