Introductory college calculus students in the United States engaged in an activity called Peer-Assisted Reflection (PAR). The core PAR activities required students to: attempt a problem, reflect on their work, conference with a peer, and revise and submit a final solution. Research was conducted within the design research paradigm, with PAR developed in a pilot study, tried fully in a Phase I intervention, and refined for a Phase II intervention. The department's uniform grading policy highlighted dramatic improvements in student performance due to PAR. In Phase II, the department-wide percentage of students (except for the experimental section) who received As, Bs, and Cs in calculus 1, compared to Ds, Fs, and Ws (withdrawal with a W but no grade on a transcript), was 56%. In the experimental section, 79% of students received As, Bs, and Cs, a full 23% increase. Such increased success has rarely been achieved (the Emerging Scholars Program is a notable program that has done so.)