Understanding and changing physical activity behaviour in university students: an ecological perspective ChenChun-Ming 2011 Studies have highlighted the prevalence of sedentary behaviours in the university student population and have noted the significant potential for the promotion of physical activity in educational settings for young adults. Following the epidemiological procedure and ecological approach, the main purpose of this thesis focused on the university student population to review the previous research results by a systematic review method (first study), to compare the differences between UK and Taiwanese participants' and relevant effective variables by using a quantitative study method (second study), to have a deeper understanding of the Taiwanese university students' physical activity behaviours by using a qualitative study method (third study), then to evaluate the efficiency of designed interventions in university settings (fourth study). The whole thesis applied the ecological approach to classify the survey variables' effect to university students' physical activity behaviours. A total of 55 published papers were reviewed and majority of studies were conducted in the US using a cross-sectional design. Finding variables consistently related to university students physical activity level were female gender(-), attitude self-efficacy perceived barrier (-), family support (+), physical activity and sport history (+). These survey variables were more consistent in the literature and corresponded to previous adults' study. Some survey variables linked to university student were also found in the literature but still need more studies for this target population to come to a robust conclusion. Seven days recall design measurement and stage of changes survey for physical activity levels were more identified and have been more frequent using in the reviewed papers. Also, more studies on different ethnicity, environmental variables and intervention with different methodology such as qualitative study method are needed to enrich the knowledge of university's students' physical activity behaviours. (Continues...).