May 15, 1999 In its conduct of monetary policy, the Bank of Canada carefully monitors the pace of monetary expansion for indications about the outlook for inflation and economic activity. In recent years, a number of factors have distorted the growth of the traditional broad and narrow aggregates. In this article, the authors discuss the uncertainty surrounding the classification of deposit instruments that has resulted from the elimination of reserve requirements and from other financial innovations. They introduce two new measures of transactions balances, M1+ and M1++ (described more fully in a technical note in this issue of the Review), that internalize some of the substitutions that have occurred. They attribute the deceleration in M1 growth in 1998 partly to the declining influence of special factors, partly to a lagged response to interest rate increases in 1997 and early 1998, and partly to some temporary tightening in credit conditions in the autumn of 1998. The broad monetary aggregate M2++, which includes all personal savings deposits, life insurance annuities, and mutual funds, grew at a steady pace in 1998, presaging growth of about 4 to 5 per cent in total dollar spending and inflation inside the target range.