The authors used a mixed-methods research design to evaluate a multi-tiered system of supports model to address the disturbing failure rates of underprepared college students placed in developmental mathematics at a small state university. While qualitative data gathered from using Participatory Action Research methods directed the two-year professional development program to implement the model, quantitative results demonstrated how the model improved learner outcomes in passing basic and intermediate algebra. Most important, follow-up analyses demonstrated that student participants went on to pass college algebra and the mathematics subtest assessed by the Collegiate Assessment of Academic Proficiency (CAAP) examination to satisfy the state's general education graduation requirements.