The focus of this study is on understanding the perceptions of middle school mathematics teachers about the implementation of standards-based grading (SBG). The study employs a multiple case design using four Connecticut middle schools where standards-based grading was in the process of being implemented. In each school, three mathematics teachers and the school principal were interviewed using semi-structured interview protocols. The interviews were coded in multiple iterations, developing categories and themes. This study found that teacher perceptions were influenced by the impetus for and method of implementation, the role of the principal, the teachers' beliefs about mathematics and pedagogy, and school and parent cultures. Implications of this research and recommendations for future research are discussed. [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.]