Concussion education is an important aspect of concussion prevention. The purpose of this study was to investigate the effect of a novel, theory of planned behavior (TPB)-driven concussion education program on secondary school athletes' concussion-reporting relevant cognitions immediately post-intervention and at 3 months follow-up. Data were collected from 428 secondary school athletes during the 2016-2017 academic year: 229 were assigned to an intervention group of which 59 (25.76%) completed assessments at all timepoints; 199 were assigned to a control group of which 153 (76.88%) completed assessments at all timepoints. Using repeated measures ANOVAs, we examined differences in athletes' concussion-reporting cognitions, by group and gender. The program had a significant positive effect on athletes' knowledge (P < 0.01), perceived behavioral control over concussion recognition and reporting (P < 0.01), and reporting intention (P < 0.01). These results were maintained at 3 months follow-up, with the exception of perceived behavioral control. The program did not have a significant effect on athletes' attitudes toward concussion reporting and subjective reporting norms. Results suggest that the TPB may be a useful framework to inform the development of more effective educational programs. There is a need for multi-layered interventions that aim to create sporting environments that encourage positive concussion care seeking behaviors.