This paper provides new empirical evidence on regional-national disparities in environmental efficiency, based on case studies of Italy and the Lazio region, which includes the city of Rome. Shift-share analyses provide evidence on the drivers of environmental efficiency and on sector specificity. This confirms the usefulness of this method for studying the environmental economics realm, in order to investigate structural and efficiency factors at the level of within country environmental efficiency performance, even in light of the different shares of services. Our evidence shows that although the Rome region has achieved higher environmental performance compared to Italy mainly thank to its being less industry based, some critical points in the energy sector and in some services should be taken into account in shaping the future development of the region. Environmental, industrial and sector-oriented policy making may also derive valuable information from the evidence provided by our study.