The present study examined the potential relationship between parenting variables and estimations of children's bicycle helmet use. Parents (N = 121) completed surveys asking about parental monitoring and questions about their bicycle habits and attitudes, as well as their expectations for their children to wear a helmet and their estimation of how often their children wear a helmet. Parents reported stronger helmet rules for their children who are beginning cyclists rather than experienced cyclists, and rules for experienced cyclists were more strongly endorsed among parents who reported more parental monitoring as well. Parents who wear helmets themselves endorsed stronger helmet rules for their experienced riders, compared to parents who do not wear helmets. Parents without helmet rules reported more peer pressure in that they were more likely to agree that their friends do not make their kids wear helmets and that their child's friends do not wear helmets. In addition, believing other parents do not wear helmets and believing one's child's friends do not wear helmets were both associated with a lower likelihood that their children wear a helmet. This appears to be the first study linking perceptions of parental peer pressure with helmet rules and use. For public health reasons, it is imperative to examine parental factors that may establish children's helmet wearing.