Persistence and progression rates for underprepared, African American, first year students entering four-year colleges is a major concern. With the consistent low persistence, progression and graduation rates of underprepared African American students in both Historically Black Colleges and Universities (HBCUs) and predominantly White serving institutions (PWIs), there lies a dire need to examine programs that will lead to a solution to this problem. The purpose of this dissertation study was to investigate the effectiveness of the implementation of a 2014 Summer School Program aimed at closing the achievement gap between conditionally (academically underprepared) admitted students and unconditionally (academically prepared) admitted students in an HBCU located in southeast Texas. More specifically, this study uses ex post facto research to determine the difference in the performance of underprepared students who were conditionally admitted summer school participants to the performance of unconditionally admitted students who were entering the university as first- time freshmen. The present study utilizes a multivariate, correlational design in order to examine the differences among independent and dependent variables through the use of Chi Square and Independent and Dependent T-Tests. These specific models were used to determine the effectiveness of the 2014 Summer School Program at one of the state's largest HBCUs. Coded institutional demographic data for the 2014 cohort was obtained. Participants for the present study were randomly selected from institutional data consisting of those conditionally accepted college students who participated in the summer school program and unconditionally accepted college students entering the university for the first time. The sample group consisted of 310 first time, incoming college freshmen. Each of the comparative study groups (treatment and control) consisted of 155 first time, first semester freshmen. The control group consisted of those incoming, traditional, African American, first time, first-semester freshmen students who met all college admissions standards and were unconditionally-admitted into the university; whereas, the treatment group consisted of those students conditionally admitted into the university and attended the Summer School Program. The results of this study indicate that there were differences between dichotomized data consisting of progression, persistence, cumulative hours completed, and gender of conditionally admitted students who enrolled in the 2014 Summer School Program and traditional, unconditionally admitted students who did not enroll in the summer school program for Fall 2014. In addition, persistence and progression rates among conditionally admitted students who enrolled in the summer school program and unconditionally admitted students who did not enroll in the summer school program for Fall 2015 and Spring 2016 were not significant. [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.]