To compare attitudes of parents who filed or considered filing an exemption to school immunization requirements and/or would not have their child immunized if it were not required by law (cases) to controls. To develop and evaluate a brochure intervention for parents considering an exemption. Interviews, focus groups, mailed surveys. Cases had more negative attitudes about vaccines than controls did. Although the brochure did not significantly improve parents' immunization attitudes compared to controls, most parents who received the intervention reported a positive impression. A science-based educational intervention for parents considering a vaccine exemption may help improve parents' opinions of childhood vaccines.