Includes bibliographical references (leaves 310-325). / xvi, 325 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A study which investigates in a South Australian context: 1. What are the physical activity gaps between social groups and how do these gaps relate to health and the other benefits of physical activity? 2. What are the contraints on choices and what needs to be done to make the choices of people to increase moderate physical activity easier? 3. What is the role of the social environment in relation to moderate physical activity choices and what needs to be done to ensure supportive environments? The results show that physical activity frequently becomes the province of differents sectors of society at different times. Recent case studies demonstrate that policies about how governments organise their services lead to more fundamental changes than specific health policies. / Thesis (Ph.D.)--Adelaide University, Dept. of Public Health, 2001