Purpose <p>Parents of individuals with disabilities often have unique lived experiences which can help improve practice and policy in special education. However, in recent reauthorizations of the Individuals with Disabilities Education Act (IDEA, the federal special education law), parents have infrequently been involved in the legislative process. To increase parent input in systemic decisions about special education, we tested a legislative advocacy program in a fully-powered randomized controlled trial.</p> Methods <p>Altogether, 45 parents of individuals with disabilities participated in the study. The legislative advocacy program was a six-hour training conducted by the Parent Training and Information Center. A series of linear regression model with multiple imputation was fitted for each outcome variable (e.g., special education knowledge, family empowerment, motivation, parent advocacy activities, and civic engagement).</p> Results <p>Immediately after participating in the program, the intervention (versus waitlist-control) group demonstrated a significant increase in special education knowledge.</p> Conclusion <p>The findings highlights the effectiveness of a legislative advocacy program in enhancing special education knowledge among parents of children with disabilities.</p>