John A. Tatom examines the effects of newly authorized money market deposit accounts and super-NOW accounts on monetary aggregate measures and monetary policy. In “Money Market Deposit Accounts, Super-NOWs and Monetary Policy,” Tatom describes the conventional view that these new accounts have distorted M1 and its interpretation while leaving M2 and its policy usefulness virtually unaffected. Disputing this conventional view, Tatom argues that the new accounts are not unprecedented. He points out that money market deposit accounts are comparable to money market mutual funds, and super-NOW accounts are similar to other checkable deposits. After investigating the impact of these past innovations, Tatom concludes that shifts to the new accounts are not likely to affect either the controllability of M1 or its relationship to measures of economic performance. In contrast, while M2 is unaffected by shifts to super-NOWs, it is pushed up by shifts to money market deposit accounts, thus altering the relationship of M2 to such measures of economic activity as GNP. Thus, the usefulness of M1 for the conduct of monetary policy is unaffected by the new accounts. On the other hand, M2’s usefulness has been reduced.