In an exploratory study, we investigated degrees of social proximity between mothers and their 9-month-old children. Twenty-four Swedish mother–infant dyads (12 boys and 12 girls) were observed during a brief free play episode. Social proximity was measured through nine items focusing on both communication and social interaction. Overall, we found that mother–daughter dyads displayed significantly higher degrees of social proximity than mother–son dyads. More specifically, mothers with daughters displayed more physical and visual contact, and were also rated as more sensitive than mothers with sons. It was also found that girls were judged as being more compliant than boys. ©1997 John Wiley & Sons, Ltd.