Objectives. This study evaluated the effects of a major federal immunization continuing education course, delivered in both traditional classroom and satellite broadcast versions, on public health professionals’ knowledge, agreement, self-efficacy, and adherence in practice to recommendations. Methods. The study used a comparative time series design to determine whether the course influenced participants’ knowledge, agreement, self-efficacy, and adherence in practice to general and polio-specific recommendations as measured immediately and 3 months after the course. It also compared the effects of the classroom and satellite broadcast versions and used path analysis to show how the outcomes were related to one another. Results. Both versions significantly improved knowledge, agreement, selfefficacy, and adherence. Knowledge and agreement were significant predictors of self-efficacy, which directly predicted adherence. Vaccine availability and supportive clinic policies were also important adherence predictors. Conclusions. A well-designed training update can change provider knowledge, agreement, self-efficacy, and adherence. Traditional classroom and distance training can have comparable effects. The findings support incorporation of distance learning in national public health training, if the distance learning is used wisely in relation to training needs, goals, and practice contexts. (Am J Public Health. 2000;90:1218–1224)