Factors associated with injury in the first year of life were examined using data on a random sample of infants in eight regions in the United States. By 1 year of age, 8.6% of the 4,989 infants surveyed had had an injury for which medical care was sought, although serious sequelae (eg, death and developmental delay) were infrequent. The data suggest that the achievement of independent mobility, eg, walking, was a major factor in the risk of injury. Other risk factors included very young mothers and isolated mothers, but not socioeconomic status, illness in the infant, or low birth weight. However, identification of small groups at very high risk is not possible, so that health professionals should be prepared to counsel all new parents early about injuries.