Effects of high-rise living on infants' development were investigated in 1987-1988 in a high-rise residential area in Tokyo, using questionnaires on the daily behaviors of a total of 1,045 infants, completed by mothers and kindergarten teachers. Infants of high-rise living showed a delayed independence in fundamental daily customs compared with those of low-rise living. This could be ascribed to an over-attachment of mothers of high-rise living with their infants resulting from a reduced number of outings.