This mixed-methods study is an investigation into the relationship between culturally responsive teaching and fourth-, fifth-, and sixth-grade student performance on the California Standards Tests (CSTs). The significance of this research lies in its evaluation of the way that the self-perceived cultural proficiency level of the teacher and self-perceived use of culturally responsive teaching in the classroom could contribute to closing the achievement gap, which exists between White-non Hispanic students and students of color and low economic status. Four suburban public school districts in Southern California participated in this study. Teachers, eligible to participate in this study within these four districts, were identified based on their students' progress on the CSTs, from the 2008-09 and 2009-10 academic years. Teachers (N = 211) were sorted into two groups: highly effective (H.E.) teachers (N = 36) and non-highly effective (N.H.E.) teachers (N = 97). Highly effective teachers were those teachers whose students increased an average of at least one and one-half proficiency level in an academic year on the CSTs in either language arts or mathematics in an academic year. Findings of this research from survey data revealed significant differences between the highly effective teachers and non-highly effective teachers in terms of two survey variables: (1) years of teaching and (2) self-identified validation of diverse cultures. Regression analyses, triangulated with interview data, revealed five predictors of highly effective teachers, which support and contradict culturally responsive teaching pedagogy. Highly effective teachers: (1) do not promote multiple perspectives in the curriculum to model and develop advocacy practices for equity and equality; (2) see students from cultures different than their own as both an individual and as a member of a cultural group; (3) set short and long-term learning goals; (4) do not teach students appropriate language for asking about other cultures; and (5) treat all students the same regardless of race, ethnicity, or family level of income. Other inquiries from surveys and substantiated with interviews provide interesting results regarding highly effective and non-highly effective teachers and will add to the literature on closing the achievement gap and have implications for teachers' professional development and student achievement on the CSTs. [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.]