This study examined gender differences in children's interaction with a baby who visited their day-care center over several weeks. Twenty-two children ranging in age from 47 to 64 months of age participated. The children's teacher filled out a questionnaire assessing each child's extraversion, activity level, and loudness. A female baby visited the day care center from one to three times a week over a two-month period. Each child's interactions with the baby were observed twice. Active, outgoing, loud girls were much more likely to interact with the baby than either quiet girls or any boys. Several of these highly interactive girls had no younger siblings. Children were found to interact with the baby more on their second observation. © 1991 Plenum Publishing Corporation.