SUICIDE—CATASTROPHIC, HEARTBREAKING, and baffling—stands out as a large social issue. The tenth leading cause of death in the United States, suicide is indeed an urgent problem. About eighty people a day kill themselves in this country. That translates into about thirty thousand people each year, or one every eighteen minutes. The problem is especially severe among young people, who have the fastest growing suicide rate of any age group.

But each suicide is also a personal tragedy. A person who kills himself or herself is not the only victim of that act. Each suicide is like a stone thrown into a pond, setting in motion a ripple effect that changes forever the lives of dozens of people who will go on living. It has been estimated that a quarter million such people, sometimes called suicide survivors, are created every year.

Researchers, psychologists, and other...