Physical activity, such as walking, is important for health. It reduces the risk of coronary heart diseases, diabetes, hypertension, obesity and some forms of cancer. Whereas traditionally research focused on individual factors, such as attitudes and socio-demographic factors, the importance of the physical environment in facilitating or constraining walking is more and more acknowledged. A better understanding of the relations between perceived environmental characteristics and walking and cycling would enable more successful interventions aimed at increasing physical activity. In this short paper we describe the preliminary results of an internet survey carried out in the Netherlands. The internet survey contains questions on walking and cycling frequencies a well as the perception of the natural and built infrastructural environment (road connections, quality of sidewalks and bike lanes, lighting, aesthetics etc.). Besides, socio-demographic variables (age, neighborhood, income etc.) are surveyed, which made it possible to control for these possibly confounding variables. Data showed that inhabitants of a strongly urbanized environment have higher frequencies of cycling than inhabitants of a non-urbanized environment. Furthermore, weight and education appear to be related to the living environment. Further Analyses are currently being conducted.