The author contends that no human endeavor can have a higher priority than the prevention of mass suicide as a result of nuclear war. He explores previous collective suicides, finding 5 common determinants: 1) sufficient group unity to allow simultaneous acts, 2) blind obedience to charismatic leaders, 3) surrender to an ideology, 4) fear of takeover by outsiders or fear of suffering so that mass death becomes acceptable, 5) technical ability to bring about mass killing in a short time. 24 Refs.