Objectives: 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. Methods: Interviews, focus groups, mailed surveys. Results: 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. Conclusions: A science-based educational intervention for parents considering a vaccine exemption may help improve parents' opinions of childhood vaccines.