We examined the effects of changes in Rhode Island's Lead Hazard Mitigation Law in 2005 on children's blood lead levels. We used 2005 to 2009 data from Rhode Island's Lead Elimination Surveillance System; city tax assessor records in Central Falls, Pawtucket, Providence, and Woonsocket, Rhode Island; and records of conformance to the state's lead hazard mitigation law, to assess the extent to which legislation changes resulted in minimizing children's exposure to lead. During the 5-year study, the proportion of properties that complied with the new law increased for properties that housed young children. However, the majority of rental properties did not comply with the law. Children's lead levels declined by approximately 1 microgram per deciliter on average in properties that did comply, demonstrating that the law could have a protective effect for children. Legislation changes increased the proportion of properties that were certified as nonhazardous, leading to decreased blood lead levels for children living in these properties. However, legislation cannot be a highly effective primary prevention strategy if it does not cover all properties where children live and is not strictly enforced.