Introduction: Stroke in young people shares traditional modifiable risk factors with older groups, and greatly affects quality of life. However, evidence on the effectiveness of educational interventions in young populations, aiming at spreading stroke knowledge and enhancing prevention, is still scarce. We evaluated baseline knowledge of stroke and possible improvements after an educational intervention among Italian high school students, also considering differences related to sex and type of school. Subjects and methods: Using a mixed educational strategy, a prospective evaluation of stroke knowledge was performed in five humanities and sciences (lyceums) and five vocational high schools of Tuscany (students of the 12th and 13th grade). A baseline assessment with a structured questionnaire (21 questions) was followed by a standardized oral presentation, using audiovisual materials. After 3 months, the same questionnaire was re-administered to evaluate the long-term impact of the educational intervention. Results: Overall, 573 students (50.8% males; age range, 17–19 years) were enrolled; 288 (50.3%) were from lyceums and 285 (49.7%) from vocational schools. Follow-up participation was 97.2%. Baseline performances were comparable between groups for most variables examined. At 3 months, all groups showed a significant improvement from baseline regarding reaction to a stroke event, identification of stroke risk factors, such as smoking (from 62.9% to 83.7%; p < 0.001) and alcohol abuse (from 49.6% to 67.2%; p < 0.001), and symptoms. Knowledge of the existence of stroke units and thrombolysis increased from 25.4% to 60.7% ( p < 0.001) and from 35.8% to 84.0% ( p < 0.001), respectively. Conclusions: Our educational intervention improved stroke awareness in high school students. The effects persisted after 3 months. Improved knowledge in young populations may reduce stroke burden in adult life, increase timely access to therapies, and spread knowledge across families.