The purpose of this study was to use the tenets discussed in the Self-Determination Theory to explore how adolescents are motivated to engage in physical activity and examine the reasons for their participation - or lack thereof - in order to determine the influence of motives on physical activity behaviors in an adolescent population. The relative autonomy continuum of the Self-Determination Theory includes amotivation, external regulation, introjected regulation, identified regulation, integrated regulation, and intrinsic motivation. These different levels will be assessed. Participants were seventh grade students at a middle school in the Phoenix metropolitan area (n=70). The adolescents’ relative autonomy levels were assessed with a modified version of the Behavioral Regulation in Exercise Questionnaire. Individual motivational factors were measured from a modified version of the Exercise Motivations Inventory. The adolescents’ locus of causality was then measured using the Locus of Causality for Exercise Scale. Participants were asked to answer two additional questions assessing their perceived time barrier and frequency of physical activity participation. The data were scored using the scoring guidelines provided by each questionnaire after collection through a Google Form and analysis on Google Sheets. Results showed that adolescents with higher levels of identified regulation (3.88), intrinsic motivation (4.22), and locus of causality (4.67) were more likely to also engage in higher levels of physical activity. These findings could be used for future research that focuses on school-based interventions for physical activity through enjoyment so as to increase identified regulation and intrinsic motivation while shifting to a more internal locus of causality in order to increase their overall leisure-time physical activity as a way to combat the increasing rates of childhood overweight and obesity in the United States.