For independent secondary schools who offer rigorous curriculum to attract students, integration of quantitative skills in the science courses has become an important definition of rigor. However, there is little research examining students' quantitative skills in relation to high school science performance within the single-sex independent school environment. To fill this gap in the literature, this study sought to determine if any relationships existed between a student's quantitative abilities, as measured by the High School Placement Test Quantitative Test (QT) score, teachers' application of math, and students' biology and chemistry grades. One hundred seventy-one students from high socioeconomic backgrounds who attended suburban single-sex independent schools in Southeastern Pennsylvania participated in this study. A two-way between-groups analysis of variance was conducted for biology courses, and a separate two-way between-groups analysis of variance was conducted for chemistry courses. Findings from this study indicated that students' QT scores and teachers' application of math have no significant relationship to students' biology grades. That is, students' biology grades were not influenced by their quantitative scores and biology teachers had generally low application of math in their courses. Findings from this study also indicated that students' QT score and teachers' application of math have statistically significant relationship with students' chemistry grades. Students' QT scores were found to have a medium, statistically significant positive effect on chemistry science grades. Teacher's application of math was found to have a large, inverse relationship with students' chemistry grades. These findings seem to suggest that school administrators may want to determine what kinds of math are being applied in the biology and chemistry classes and whether both curriculums need to be reconstructed to allow students to utilize quantitative skills. [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.]