Since 1992, the Committee on National Statistics (CNSTAT) has produced a book on principles and practices for a federal statistical agency, updating the document every 4 years to provide a current edition to newly appointed cabinet secretaries at the beginning of each presidential administration. This second edition presents and comments on three basic principles that statistical agencies must embody in order to carry out their mission fully: (1) They must produce objective data that are relevant to policy issues, (2) they must achieve and maintain credibility among data users, and (3) they must achieve and maintain trust among data providers. The book also discusses 11 important practices that are means for statistical agencies to live up to the four principles. These practices include a commitment to quality and professional practice and an active program of methodological and substantive research.