The purpose of this study was to examine possible relationships between participation in extracurricular activities and student achievement, participation in extracurricular activities and attendance, and participation in extracurricular activities and behavior. The setting for this study was a high school in western Nebraska. Data for 275 of the school district's 2007-2008 and 2008-2009 high school graduates were obtained from the high school activities office and the school district's student management system. Ten research hypotheses were tested using appropriate statistical analyses. Relationships were found for five research hypotheses: (1) Students who participated in extracurricular activities had higher grade point averages than students who did not participate. (2) Students who participated in extracurricular activities had a higher rate of school attendance than students who did not participate. (3) Students who participated in only sport activities received more disciplinary referrals than students who participated in only non-sport activities. (4) Students whose families have a higher level of socio-economic status were more likely to participate in extracurricular activities. (5) White students were more likely to participate in extracurricular activities than Hispanic and other racial ethnic backgrounds. No relationships were found for five research hypotheses: (1) Between grade point averages of students who participated in only sports activities and grade point averages of students who participated in only non-sport activities. (2) Between attendance of students who participated in only sports activities and attendance of students who participated in only non-sport activities. (3) Between participation in extracurricular activities and disciplinary referrals. (4) Between grade point averages of students who participated in only sports activities, grade point averages of students who participated in only non-sport activities, and grade point averages of students who participated in both sport and non-sport activities. Between attendance of students who participated in only sport activities, attendance of students who participated in only non-sport activities, and attendance of students who participated in both sport and non-sport activities. [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.]