This paper aims to analyse empirically the intricate relationship between urban sprawl and commuting, a process that started a few decades ago in Italy. Using a mobility impact index based on commuting data for 1981 and 1991, we quantify the impact of commuting for seven major Italian urban areas, comprising in total 739 municipalities (communes). Our modelling experiment highlights the effect of sprawl at the commune level, while taking into account the variability of communes across geographical location and level of polycentrism. Causal relationships between spatial developments and explanatory factors related to changes in urban density are analysed using multivariate cross-section regression analysis and Causal Path Analysis (CPA). Our empirical results confirm the expectation that sprawl is accompanied by intensive travel movements and associated environmental effects.