Several international jurisdictions allow family exemptions to graduated driver licensing passenger restrictions. The objective of this research was to examine differences in injury risk to US child passengers in crashes involving sibling versus non-sibling teen drivers, and to compare outcomes with crashes involving adult drivers. Insurance claim and telephone survey data were collected on 16 233 child passengers (representing 289 329 children) in 17 US jurisdictions. There was a trend toward higher restraint non-use by child passengers in the non-sibling group than in the sibling group (9.6% vs 4.7%; p = 0.08). Children in the sibling group had a 40% lower risk of injury than those in the non-sibling group (adjusted OR 0.60, 95% CI 0.40 to 0.90); however, injury risk was higher in the sibling group than in children traveling with adults (adjusted OR 1.57, 95% CI 1.09 to 2.26). Child passengers riding with sibling teen drivers may be safer than those riding with non-sibling teens, but not as safe as those riding with adult drivers.