Many European cities are experiencing an apparent shift in mobility patterns. Walking and cycling are becoming increasingly popular, while many households are deciding not to have a car. These trends feed into a new concept of urban proximity, within which walking is to be considered as a transport mode in its own right. However, little is known about the social and spatial determinants of urban walking, which is why the present study seeks to ask the two following questions: What is the profile of urban walkers in the five largest conurbations in Switzerland: Basel, Bern, Geneva, Lausanne and Zurich? And to what extent can the level of walking in a given area be explained by urban density or urban function (mainly residential; mainly employment; mixed residential and employment)? To answer these questions, we analysed data from the 2010 Swiss transport micro-census using a quantitative and spatial approach, introducing sub-sectors which we characterised according to jobs/residents ratios and measures of urban density. Results show that urban density and urban function do play a role in stimulating or impeding walking behaviours, but this effect is weak compared to the effect of individual characteristics. Intriguing differences were found between the French-speaking cities, Geneva and Lausanne, which display significantly more walking, and the three German-speaking cities, which have less walking but better public transportation systems. The article concludes with a contribution to the research agenda: that the link between walking and public transport use in medium-sized cities should be investigated at the European level.