This paper aims to analyse the validity and reliability of National Competitiveness Indices which are composite indicators ranking countries according to selected criteria and measures of national competitive powers. For this, it assesses the best-known indices, The Global Competitiveness Report of the World Economic Forum and The World Competitiveness Report of the IMD, and finds deficiencies at several levels. Its definitions are too broad, the approach biased and the methodology flawed. Many qualitative measures are vague, redundant or wrong. In particular, the extensive use of local executive responses, with many questions posed in an unclear manner, raises too many doubts to allow the data to be used to rank countries in the way the two organisations do. The impressive pyramids of rankings and policy conclusions reached by WEF and IMD rests ultimately on a small, inadequate and often suspect base. These weak theoretical and empirical foundations reduce the value of the indices for analytical or policy purposes. To be analytically acceptable, the two indices should be more limited in coverage, focusing on particular sectors rather than economies as a whole, and using a smaller number of critical variables rather than pulling in everything the economics, management, and other disciplines suggest.