Cigarette smoking is the leading preventable cause of death in the United States. Environmental and policy interventions, particularly tobacco-control laws and regulations, are an important means to prevent and reduce tobacco use. For this study, preemptive legislation was defined as legislation that prevents any local jurisdiction from enacting restrictions that are more stringent than the state law or restrictions that may vary from the state law. One of the national health objectives for 2000 is to reduce to zero the number of states with preemptive smokefree indoor air laws (objective 3.25); a proposed objective for 2010 is to reduce the number of states with any preemptive tobacco-control laws to zero. To document trends in preemptive tobacco-control legislation at the state level, CDC identified state preemptive provisions and their effective dates from June 1982 (the oldest provision currently in effect) to September 1998. This report summarizes the results of this analysis, which indicate an increase in the number of preemptive provisions from 1982 to 1996; no preemptive provisions in tobacco-control laws have been enacted since 1996.