This report was written as one of UNESCO's inputs to the first phase of the World Summit on the Information Society (WSIS) in 2003. Its focus is on measurement issues with regard to Information and Communication Technologies (ICTs) and gives an overview of the data that exists as well as where the gaps lie. Issues relating to data quality are also addressed. The overall aim of the report is to support the development of national, regional and international data systems and indicators that are comprehensive, policy relevant and reliable for the proper understanding, monitoring and development of a sustainable and equitable Information/Knowledge Society. The first part of this report includes stocktaking of selected global ICT data from a variety of sources. This is followed by a discussion on the limitations of the existing data as well as barriers and problems that might be encountered in collecting such data. The final section of the report discusses what data might be of value to collect in the future. The report concludes with a series of recommendations.