The single largest contributor to infant mortality in the District of Columbia, and elsewhere in the United States, is immaturity. In the district the dead newborns are not simply those born a little too early; they are extraordinarily premature, babies weighing less than 2 pounds 4 ounces at birth. The cause of their premature birth is not known. It is not just teenage pregnancy, poor maternal nutrition, infectious disease, cigarette smoking, drug abuse or alcoholalthough each of these is statistically associated with an increased risk for early delivery. The major common factor repeatedly identified is poverty. It is apparent that the overriding influences on infant mortality are social and cultural, not medical.