This study evaluates the effectiveness of the James Madison Legacy Project (JMLP) in achieving positive student knowledge outcomes as a result of teachers’ participation in the professional development (PD) program. Middle and high school teachers were randomly assigned at the school level to either a traditional PD program using live scholars or a hybrid PD program that incorporated digital resources. The research employs a randomized control trial to evaluate students’ acquisition of civic knowledge from teachers who received the traditional JMLP PD, hybrid JMLP PD, or did not receive the PD. The findings indicate that the effects of the interventions on student knowledge are positive and statistically significant for both middle and high school. Middle and high school students whose teachers participated in the JMLP saw greater improvement in their civic knowledge scores from pretest to posttest than did control group students. JMLP students scored significantly higher on civic knowledge tests after taking a civics class than students in the control group regardless of whether their teachers participated in the traditional PD or hybrid PD program. The differences in mean knowledge scores for students in the traditional PD and hybrid PD groups are small, which supports the case for the scalability of the JMLP PD program using scholar videos and digital resources.