This quantitative study examined the effects of extracurricular activities on academic achievement of seventh and eighth graders. This study compared the academic achievements of participants and non-participants in Mathematics and Language Arts. The three different measurements used for the academic achievement were TCAP, ThinkLink, and GPA scores. Students were also administered an attitude survey. The differences between participants and non-participants were significant. The participants outscored the non-participants in TCAP and ThinkLink tests. The difference in GPAs was not significant. The students who participated in extracurricular activities had a better social and academic outlook. Participation in extracurricular activities clearly appeared to have influenced academic achievement positively. [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.]