A quantitative, causal-comparative study between single gender and traditional mixed gender schools was conducted to examine how single gender schooling affected the academic achievement of African American males in a high-poverty urban community. This study examined the differences in TSI and EOC scores between African American males who attended a single gender male high school and a traditionally mixed gender high school serving students in the same community in Fort Worth, Texas. A two sample t-test was used to compare the STAAR and TSI scores of the two groups of African American males. Microsoft Excel was used to collect the descriptive statistical data and analysis was conducted in SPSS version 25.0 for Windows. A detailed description of the participants, the research design that was used in the study, a description of instruments that was used to analyze the data, research problem, research questions on which the study was based, and a description of data analysis methods that was used. This quantitative research compared the STAAR and TSI scores in language arts, math, and reading. The findings of study indicate the single-gender school model impacts the academic achievement of African American males in a particular community in Fort Worth, Texas. The single-gender school had 100% of the African American males in its first graduating class during the 2017-2018 school year were accepted into college. [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.]