The main topics treated in this conference volume are problems of deflation and quality change, the adequacy of the data used to construct the U.S. national accounts, and the broad theoretical evolution of the U.S. national income and product accounts. As these topics suggest, this volume represents a new stage in the study of national income and product accounts in that emphasis is placed on the information content of the system rather than on the structure of the accounts. This new emphasis is highlighted by the inclusion of a discussion among prominent users of the national accounts—Lawrence Klein, Otto Eckstein, Alan Greenspan, and Arthur Okun—that indicates the difficulties that confront those who utilize this information.