Changes in United States infant and perinatal mortality during the period 1965-1973 are examined by race, age at death or length of gestation, and degree of urbanization. Several improvements in mortality rates are identified and discussed in relation to changes in the United States which have occurred in economic conditions and standards of living, in medical techniques and the organization and availability of health services, and in the demographic characteristics of the child-bearing population. Each of these changes was in a direction which would be expected to have a favorable effect on infant and perinatal mortality. Approximately 100 pages of data are included. (Author/JMB)