Frequency of participation in organized activities and informal play contacts with other children were investigated for a group of 118 children with Down's syndrome. Measures were based on mothers' reports. As part of a study of child and family functioning, a wide range of child, parent and family variables was measured and the relationships of these to the extent of the children's social contacts were investigated in multivariable analyses. Family variables of social class, parental education, marital relationship, and achievement and recreational orientation were found to be significantly related to the measures of the child's social life. In addition, children at the lower end of the IQ range in this sample were likely to have fewer informal play contacts. These results point to the influence of the family in stimulating and maintaining the children's social activities.