Adolescence is a critical time for developing lifelong healthy behaviors, including active lifestyles. Participation in sport and physical activity, however, declines during adolescence, and few studies have comprehensively identified why, particularly among rural girls. This article identifies a range of independent and interacting factors that influence sport and physical activity participation of rural adolescent girls. The socioecological model of health was used to guide four focus group discussions with Grade 7 girls (n = 34). The results showed that adolescent girls were positively influenced when sports or physical activities were fun, when they involved being with friends, and when they were supported by families and teachers through role modeling and positive feedback. A range of intrapersonal and organizational factors affected perceived self-competence, particularly the coeducational nature of school physical education classes and peer teasing, which supported social comparisons of skill level. In promoting sport and physical activity to rural adolescent girls, focus must be directed on developmentally appropriate activities that are fun, offering opportunities for single-sex classes, and generating cultural changes that encourage noncompetitive and self-referencing activities.