Recent information society policies have been paying much attention to the threat of a "digital divide". The gap between citizens from different socio-economic backgrounds with regard to their opportunities and abilities to access and use information and communication technologies is commonly regarded as a potential barrier for participation in the information society. This paper suggests a method for measuring the digital divide on an aggregate level by defining a Digital Divide Index (DDIX) which focuses on the presumably disadvantaged groups of society. The DDIX applies diffusion theory to the current digital divide research paradigm. It presents initial results for the 15 EU Member States and the European Union as a whole. A comparison of the indices for the years 1997 and 2000 shows that the digital divide within Europe has not yet decreased and that particularly the elderly and the low education segment of the population have failed to catch up with the average. Furthermore there is evidence of a polarisation between those countries who manage to foster an inclusive information society and those who do not. The paper reports about research in progress which is linked to several indicator projects funded within the IST Programme of the European Union, especially to the projects SIBIS, BEEP and SeniorWatch.