Investigated whether control exerted through supervision is believed by mothers to reduce risk of unintentional injury to their children. 150 mothers of 1-, 2-, and 3-year-old children rated the risk of their child having an injury and indicated what injuries they anticipated in different rooms of the home under four conditions of supervision. A clear effect of supervision was observed in that rated risk and the number of anticipated injuries decreased depending on whether the mother was in the same room or not. Furthermore, a decrease was found when the mother was in the same room engaged in the same activity as the child (either playing with or being assisted by the child). The observed effects of supervision were less strong for older children and for rooms perceived as less dangerous.