New composite index of transparency developed for 197 countries between 1980 and 2010. * Index divided into 'information' (ITI) and 'accountability' (ATI)sub-indices. * Countries often differ substantially in their ITI and ATI scores eg China, Singapore. * May be a useful tool to examine many issues surrounding transparency. Interest in the political and economic consequences of transparency has grown significantly over the past decade. The literature, however, has been hampered by methodological issues over what actually constitutes 'transparency', as well as the lack of a quantitative indicator that has substantial coverage across countries, and time. This paper uses a relatively new methodology, similar to Transparency International's Corruption Perceptions Index, to construct composite indicators of what we call Informational Transparency, and Accountability. These new indicators use data from 29 sources, with scores being derived annually between 1980 and 2010 across more than 190 countries.