Relatively little research has investigated the impact of parental cancer on developmental outcomes for school-aged children beyond the home. The current study was designed to examine the impact of maternal breast cancer on the social behavior, peer acceptance, and friendships of children and adolescents at school. It was hypothesized that children of women with breast cancer would have fewer friends and be viewed by peers, teachers, and themselves as more socially isolated than comparison classmates. A sample of 60 school-aged children (age 8-16) of women with breast cancer, 58 teachers, and 1138 classmates provided data in classroom settings. Comparisons were made between children in the maternal cancer sample and 60 classmates matched for gender, race, and age. No overall group differences were found on indicators of peer acceptance or friendships at school. Although marked behavioral similarities were found between groups, analyses indicated that sons, but not daughters, of mothers with breast cancer were seen by teachers and peers as more socially sensitive and isolated than comparison peers. Further research is warranted to confirm findings that sons of mothers with breast cancer may experience social isolation and to examine the stability and consequences of this behavioral pattern. (c) 2007 John Wiley & Sons, Ltd