This study sought to determine whether a relationship existed between teacher-assigned classroom grades and high-stakes test scores. The study examined teacher-assigned math grades in correlation to the student scores on the Florida Comprehensive Assessment test (FCAT) in a selected Florida high school. It also sought to determine the relationship between teacher-assigned classroom grades and high-stakes testing scores independent of the variables of gender, ethnicity, disability status, and Limited English Proficiency Status. Hence, there were two main research questions that drove this study: (a) Do tenth-grade classroom math grades relate to the student's performance on the math portion of the FCAT, and (b) After controlling for student characteristics (gender, ethnicity, disability status, and Limited English proficiency), is there a significant relationship between tenth-grade classroom math grades and students' performance on the math portion of the FCAT? The raw scores were taken from the available sample of tenth grade students whose test scores and classroom grade scores were reported from their tenth-grade year during the 2009-2010 and 2010-2011 school years. A quantitative, non-experimental correlational approach was used to determine if there is a correlation between the students' classroom grades and their FCAT scores. Correlational coefficients were produced to reflect the strength of the relationship between the independent variable, teacher-assigned grades, and the dependent variable, the FCAT. A Pearson correlation was used as the statistical technique to determine the relationship between the independent variable and the dependent variable. A multiple regression was used to determine the strength or existence of a relationship of the independent variable and the dependent variable independent of gender, ethnicity, disability status, and Limited English Proficiency status. This information will assist in developing high school grading models that can be used to produce grades that are strongly indicative of student achievement towards classroom preparation of mastering standards for state assessments. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]