This article presents an educational action research study examining how one online, classroom-based role-play simulation offers middle school students the opportunity to strengthen their agency and voice. The Jewish Court of All Time (JCAT) is a web-mediated simulation designed for middle school classrooms where students take on roles of various characters throughout the world, history and literature to address an imaginary court case. JCAT is meant to develop students' skills in writing, critical thinking, perspective-taking, historical empathy and communication, as well as subject literacy in social, historical and cultural contexts. Our research question focuses on how JCAT further encourages and supports the middle school students' agency and voice. We examine how students exercise their agency and voice both in the online environment and in accompanying classroom activities. As an educational action research study, we focus on simulations in which at least one of the authors was a participant, and also pay special attention to how our findings can enhance future simulations. Findings suggest that students constructed knowledge of democratic ideals and were able to exercise their agency and voice specifically, both in the online environment and in accompanying classroom activities.