To expand and improve evidence of grading practices, we seized an opportunity presented by the implementation of standards-based grading practices at 11 high schools in Jefferson County Public Schools in Louisville, Ky. These high-needs schools faced substantial sanctions outlined by recently revised federal and state policies unless they made substantial improvements in state standardized test results. To dramatically increase the number of students meeting proficiency benchmarks, principals and teachers from the 11 high schools collaborated with district personnel to establish a competency-based instructional initiative. The teamwork between school and district-based educators resulted in Project Proficiency. For each grading period, Project Proficiency required teachers to focus on three key standards per grading period. School and district-based content specialists derived these 18 standards from the content of the state algebra curriculum. Teachers created formative assessments that measured student progress in each standard. If a student did not demonstrate competency, teachers developed interventions that focused specifically on the student's identified needs. Finally, schools participating in Project Proficiency adopted testing procedures that supported reassessment of students until they reached proficiency. Compared to traditional grading, standards-based grading practices demonstrated stronger correlations between grades and standardized test scores, including among minority and economically disadvantaged students. In addition, students who experienced standards-based grading more often earned an A or B and scored higher on the standardized state test. Although we discovered statistical benefits to standards-based grading practices, we wondered how these differences translated into real students, grades, and test results.