The influence of severity of closed head injury and age on attentional functioning was prospectively investigated in 36 children (age range, 7 to 16 years) 6 months after injury. Children were placed into mild, moderate, and severe injury groups using established neurologic criteria. Each child received the Wechsler Intelligence Scale for Children-Revised Digit Span subtest and a continuous performance test. Children with severe closed head injury demonstrated significantly poorer continuous performance test scores than mildly or moderately injured children. Injury severity had no effect on Digit Span scores. Younger children exhibited more pronounced impairment on the continuous performance test relative to uninjured age peers. These results extend the persistence of attentional impairments beyond those of previous reports. Closed head injury is not associated with preferential sparing of sustained attention in younger children 6 months after injury. Brain injury earlier in life may result in delayed vulnerability of information processing skills.