Sprawl, as a particular characterisation of spatial extension of urbanised areas, is a contested issue. In this paper we provide an analysis of the major socio-economic determinants of changes in those urban patterns considered as sprawl in Switzerland. Our analysis covers the years 1980–2010, and has been conducted for all of the 2495 Swiss municipalities. The spatially explicit model gives evidence of the importance of spillover effects. Employing regression modelling of different urban sprawl metrics that capture urban development patterns we show that the socio-economic explanatory variables yield different results in explaining those metrics and thus give insights in the highly complex matter that is sprawl. These metrics which include the extent of built-up areas, dispersion of settlements and utilisation density provide a composite metric for urban sprawl. Our results show that the densification of built-up areas gains increasing influence in shaping urban patterns and that, in Switzerland, accessibility is a key determinant of sprawl.