This quantitative research study used logistical regression and ordinary least squares to examine factors that contribute to the narrowing of the achievement gap at an urban high school in the Midwest. The study analyzed the relationship between five independent variables related to participation in co curricular activities, demographic characteristics of individual students, and four dependent variables related to academic achievement at a large urban high school in the Midwest. The independent variables included the following: major, minor, and non-participation in co curricular activities, student background, and socioeconomic status. In this study, academic achievement was defined by high school class rank, grade point average, whether a student took the ACT exam and performance on the ACT exam. A database of 1,440 students who graduated over a four year period from the large urban Midwestern high school between 2003 and 2006 was utilized. Major participation in co curricular activities had a statistically significant and positive influence on grade point average, high school class rank percentile, and performance on the ACT exam. However, co curricular participation was not found to have a statistically significant influence on the probability that a student takes the ACT exam. [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.]