The major purpose of this study was to ascertain how intermediate grade teachers' culturally relevant beliefs and practices might contribute to mastery proficiency for African American students on New York State English Language Arts (ELA) and mathematics assessments. The study measured how teachers in similar high need suburban elementary schools in intermediate grades 3-5 described their culturally relevant beliefs and practices. A survey instrument was administered to 66 teachers who taught predominantly African American students. The majority of these schools had over 50 percent poverty status determined by the combined free and reduced lunch status. The schools were categorized into two groups determined by high and low mastery scores on the New York State ELA and mathematics assessments. How teachers differed in their descriptions of Students' Needs and Strengths, Cultural Assets, Social Relations Inside and Beyond the Classroom, Conceptions of Knowledge/Student Learning and Conceptions of Self and Students were examined. The results of this study indicated agreement to strong agreement with how teachers described themselves to endorse Students' Needs and Strengths, Cultural Assets, Conceptions of Knowledge/Student Learning (Positive), and Conceptions of Self and Students (Positive). A difference that approached significance between African American and White teachers inferred African American teachers maintained beliefs and practices that built more on Students' Needs and Strengths and Cultural Assets than White teachers. Moderately strong correlations among these variables suggested they might contribute to mastery achievement for African American students on 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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]