Introduction: Attention-deficit/hyperactivity disorder (ADHD) symptoms have a negative impact on children's cognitive, emotional, behavioral, social, and academic performance. Therefore, greater focus should be directed toward increasing awareness of this condition. Aim of Work: To evaluate the effect of an interventional educational program focused on ADHD knowledge among elementary school teachers. Materials and Methods: A Randomized Controlled Trial was conducted among 72 elementary school teachers in the Zagazig educational administration, Sharkia governorate, Egypt, during the second term of the 2021–2022 school year. Sample participants were selected from the elementary schools' teacher lists provided by the educational administration using a simple randomizing technique and were divided into two groups. Each group (control and intervention) included 36 teachers assigned in matched pairs. Both groups had their knowledge regarding ADHD assessed using a predesigned scale (Knowledge of Attention Deficit Disorders Scale) (KADDS) and were reevaluated three months later after the educational intervention was administered to the intervention group. Results: A statistically significant improvement was observed among teacher knowledge regarding ADHD postintervention in the intervention group compared to the control (p = 0.001). Conclusion and Recommendations: Educational interventions significantly improved teachers' understanding of ADHD and will allow them to better support students who have ADHD. The possibility of incorporating an ADHD knowledge enhancement program into teacher education and preparation programs should be considered.