It has long been known that suicidal behavior varies strikingly across the life span. One example is the ratio of nonfatal to fatal suicide attempts, which goes from about 20:1 in youth to 4:1 in the elderly. In this issue, we have asked leading investigators in suicidology to produce a set of critical reviews of the scientific literature on suicidal behavior across the lifespan. This issue gives the reader a birdÕs eye view of the field with special emphasis on unanswered research questions that are relevant for clinical care. The issue is organized to cover different spectra of risk at major developmental stages: familial effects on suicidal behavior; the effect of early childhood experiences on later suicidal risk; phenomenology of child and adolescent suicidal behavior; and suicidal behavior in adulthood focused on two higher risk groups, nonfatal attempts in young women and suicide in elders.