The use of active learning pedagogies gives students a more applied experience and aids in the retention of material, improvement of critical thinking, and overall student satisfaction. Among these pedagogies, long-form (complex, extended) simulations provide an excellent vehicle for teaching students about the legislative process. However, these simulations can be time-consuming and organizationally taxing. We use LegSim, an online simulation platform, to overcome these difficulties. LegSim allows for the easy execution of key simulation activities, such as bill introduction and referral and voting. It facilitates the organization of large quantities of information including legislative proposals, party rosters, caucus rosters, committee rosters, committee reports, and member participation. As a result, we have been able to incorporate substantial complexity into our legislative process simulations while keeping the task of administering the simulation manageable. Students represent real districts/states, introduce and cosponsor legislation, work in party groups and in committees, develop familiarity with legislative procedures and norms, and debate and vote on legislation. In this essay we discuss the key features of LegSim, explain our primary goals and design choices for the simulation, and reflect on students' reaction to this kind of pedagogical activity.