Twenty-five years after the eradication of smallpox, the ongoing effort to eradicate poliomyelitis has grown into the largest international health initiative ever undertaken. By 2004, however, the polio eradication effort was threatened by a challenge regularly faced by public health policymakers everywhere-misperception about the benefits and risks of vaccines. The propagation of false rumors about oral poliovirus vaccine safety led to the reinfection of 13 previously polio-free countries and the largest polio epidemic in Africa in recent years. With deft management of such challenges by local, national, and international health authorities, poliomyelitis, a disease that threatened children everywhere just 2 generations ago, could soon be relegated to history like smallpox before it.