This book deals with many of the most relevant topics in price index numbers theory and practice. The problem of the harmonization of CPIs and the time-space integration of baskets is analyzed at the Eu-zone level, with methodological and actual proposals on how to proceed for an overall treatment of the matte. Likewise, the construction of sub-indexes for households economic and social groups is investigated, in order to obtain specific inflation measurement instruments. Evidence from most updated databases is given. The questions of the spatial comparisons of price levels through PPPs and the international comparisons of macroeconomic aggregates, namely incomes, are approached, in an econometric model framework as well. Moreover, the index numbers theory is re-considered, also in an axiomatic perspective, as well as the measurement of production in non-market services is examined. Deflation problems are analyzed too, with examples taken from the national statistical offices experience. Finally, the price indexes in financial markets are discussed, with emphasis both on methodological issues and empirical applications.