Many adolescents are not physically active enough to receive associated health benefits. Furthermore, participation in physical activity generally declines during adolescence, and to a greater degree for females. Longitudinal research is required to better understand the determinants of change in physical activity by adolescent females to inform physical activity-related policy and practice. This study explored patterns of change in socioecological factors hypothesised to be associated with physical activity and sport, across the adolescent period for females.This longitudinal study employed three annual surveys of females from metropolitan and non-metropolitan areas recruited in Year 7 (n = 328) and Year 11 (n = 112). Self-report measures included questions regarding general barriers to participation, as well as factors relating to the socioecological domains.The barriers where significant changes within or differences between cohorts were observed were mostly intrapersonal (lack of energy, lack of time due to other leisure activities). Lack of time was more prevalent in the Year 11 cohort than in the Year 7 cohort. Perceived importance of life priorities mainly related to education and study and more so for the Year 11 cohort. Perceived competence declined for the Year 7 cohort. Support from family and peers trended downwards in both cohorts, whereas access to facilities increased both within and between cohorts.Significant patterns of change in the determinants of physical activity participation were observed across the adolescent period. It is important to consider flexible structure and scheduling of physical activity and strategies to develop competency in childhood and early adolescence.