This study explored the relationship between student adjustment theory and college student health behaviors. Specifically, this research examined first-year freshmen college student physical activity and nutrition behaviors and impact on adjustment to college (N = 37,564). The design for this study was a non-experimental "ex post facto" examination of archival data provided by the American College Health Association's National College Health Assessment II survey, spanning academic years 2008 through 2009. The main variables in this study included student physical activity and nutrition behaviors. Baker and Siryk's student adjustment theory was used as a theoretical framework to identify survey questions related to academic, personal-emotional, and social adjustment. A significant, positive correlation was found between students who engage in physical activity and healthy eating behaviors and level of student adjustment. In addition, students who reported meeting national recommendations for physical activity and fruit and vegetable consumption exhibited significantly greater academic, personal-emotional, and social adjustment. The results of this study indicate a need for further research on the effects of physical activity and nutrition on college student adjustment. Furthermore, the results can be used as a foundation for educational programming for higher education professionals. [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.]