In a flipped classroom, an increasingly popular pedagogical model, students view a video lecture at home and work on exercises with the instructor during class time. Advocates of the flipped classroom claim the practice not only improves student achievement but also ameliorates the achievement gap. We conduct a randomized controlled trial at West Point and find the flipped classroom produced short-term gains in math and no effect in economics. The flipped model broadened the achievement gap: Effects are driven by white, male, and higher-achieving students. We find no long-term average effects on student learning but the widened achievement gap persists. Our findings demonstrate feasibility for the flipped classroom to induce short-term gains in student learning; however, the exacerbation of the achievement gap, the effect fade-out, and the null effects in economics, suggest that educators should exercise caution when considering the model.