Reliable and consistent time series are essential to any kind of economic forecasting. Skills forecasting needs to combine data from national accounts and labour force surveys, with the pan-European dimension of Cedefop's skills supply and demand forecasts, relying on different international classification standards. Sectoral classification (NACE) and occupational classification (ISCO) standards underwent substantial changes in recent years, related not only to internal structure but also the logic of how companies or workers are classified. It is natural that changes to key classification standards had significant impact on this pan-European exercise but Cedefop has developed methodology to overcome this problem and to find the best match between the old and new classifications. This publication details Cedefop's action, which should also have value for those dealing with labour market analysis at national level. The following are appended: (1) General limits of the LFS-based database; (2) Cedefop pan-European forecasting model of skills supply and demand; and (3) Detailed results of employment share analysis. [This research paper is based on contributions from Terry Ward, Robert Stherer (Alphametrics), and Rob Wilson (Institute for employment research University of Warwick. This project is supported financially by the progress programme, a European Union programme to promote employment and social solidarity (2007-13).]