The purpose of this study was to explore teachers' perceptions of grading policies and practices. A phenomenological study was pursued as the method allows for a deeper, more meaningful investigation into the lived experiences of subjects. In this case, a sample of secondary teachers working for a district that has recently adopted a mastery-based grading policy. This study sought to answer the following questions: RQ1: How do secondary teachers understand grading student work within the context of the district's mastery-based grading policy? RQ2: How do secondary teachers practice grading students' work within the district's mastery-based grading policy? RQ3: How do secondary teachers' personal beliefs about grading students' work factor into the successful implementation of the district's mastery-based grading policy? Findings were examined through Festinger's Theory of Cognitive Dissonance. Themes revealed that there are wide-ranging emotions associated with grading systems and policies, which complicates their implementation and delivery. Therein, understanding teacher perceptions of grading policies and practices may support policymakers and educational leaders in future grading policy decisions that overwhelmingly support increasing grading validity. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]