IN 1974, the Board of Governors of the Federal Reserve System appointed an advisory committee to study the definition and estimation of the monetary aggregates.l Its report [16] was released two years later, and supporting papersprepared by the board staffbegan to appear in 1978 (e.g., [17]). Respondingto the recommendations developed, it has recently proposed a set of revised monetary aggregates intended to supplant those in use the past ten years [33].2 This paper reviews the development of these new statistics. Part 1 describes the proposed aggregates and analyzes the supporting evidence. Although the proposed definitions have substantial intuitive appeal in the current regulatory environment, the weakness of the empirical evidence and the likelihood that regulatory changes will render several of the proposed aggregates obsolete argue against their immediate adoption. Part 2 extends the board staff analysis of seasonal and transitory variations in the monetary statistics, recommendations intended to sift the signal from the noise in incoming data. Two other important issues not reflected in the proposed definitions