Goldstein ND, et al. - Researchers intended to determine if there is an association between vaccine-preventable disease (VPD) incidence and proposed state vaccine exemption legislation. The incidence of VPD outbreaks in the United States is increasing. A major factor in the transmission of the disease has been susceptible, nonimmune children whose parents have opted to exclude them from vaccine requirements for school entrance. Previous research showed a related increase in the volume of exemptions introduced by the state legislation.