Although safety rules are one of the primary preventative tactics used by parents to avoid childhood injury, very little is known about how rules are applied within families. In this preliminary study in the area of application of family safety rules, we found that mothers tended to impose rules consistently more often than inconsistently, and where they were inconsistent, they tended to regard a risky behavior as unacceptable, even if there was no family rule outlawing the behavior. The number of rules was negatively related to the number of injuries, suggesting that rules may indeed have the preventative properties that parents believe them to have. The importance of understanding how rules may prevent or fail to prevent injuries is underlined and future research challenges are described.