Background. Asthma is an inflammatory condition of the bronchial airways. The majority of asthma education interventions target adults and children, while few exist for the adolescent population. Among adolescents, asthma is an important cause of morbidity and mortality. Effective theory-based asthma education interventions, designed specifically for the adolescent population, are needed. Purpose. This study evaluated the effects of an adolescent asthma education intervention, based in part on social cognitive theory, on knowledge, intention, behavior, self-efficacy, and self-consciousness. Method. The sample consisted of 87 participants from six middle and/or high schools. The research was based on a nonequivalent comparison group design with delayed intervention in one comparison group. Questionnaires were administered at baseline, at immediate post-intervention, and five weeks after the intervention. Results. When comparing those in the intervention (n = 51) and comparison groups (n = 36), there were no statistically significant differences found. After collapsing across groups, however, statistically significant improvements from baseline to immediate post-intervention were found for knowledge, intention (when alone), self-efficacy, spacer use, peak flow meter use, and number of days a peak flow meter was used in the past week. In addition, statistically significant improvements were found from immediate post-intervention to five-week follow-up for peak flow meter use and number of days a peak flow meter was used in the past week. Furthermore, statistically significant improvements were found from baseline to five-week follow-up for intention (when alone), spacer use, peak flow meter use, number of days a peak flow meter was used in the past week, and number of days a spacer was used in the past week. Conclusion. The evaluation of this theory-based asthma education intervention showed the positive impact this curriculum can have on a sample of asthmatic adolescents.