Injuries are the leading cause of death and disability among young children and caregiver supervision is an important factor that influences risk of injury. Research suggests that young children's risk of injury is increased when supervised by an older sibling, but no observational data exists to verify this. The current study compared observed interactions between maternal/older sibling supervisors and supervisees ('N'=49) in a setting having "contrived hazards" (i.e., objects that appeared to pose a risk of injury but had been altered to eliminate risk). Results revealed that mothers used more proactive safety behaviours, while older siblings more often modeled risk taking. Supervisees displayed more risk taking when supervised by a sibling, yet sibling supervisors failed to watch these supervisee risk behaviours more often than mothers. Implications for children's risk of injury during sibling supervision and directions for future research are discussed.