Neurodevelopmental outcomes of human immunodeficiency virus Type 1 (HIV-1)-infected infants of non-drug-using mothers were assessed in a controlled, prospective study from birth to 24 months with 3 groups: 61 infants of HIV-infected mothers, 234 uninfected infants of HIV-infected mothers (seroreverters), and 115 uninfected infants of uninfected mothers. Compared with seroreverters and uninfected infants, HIV-infected infants demonstrated lower mental and motor development on the Bayley Scales and greater deceleration in their rate of motor development. HIV-infected infants with abnormal neurologic exams had lower motor and mental test scores and lower rates of motor Bayley Scales scores than their HIV-infected counterparts with normal neurologic exams. Contrary to prediction, no group differences in mean performance or growth rates were found on visual information processing on the Fagan Test of Infant Intelligence.