THIS PAPER considers whether monetary policy and banking supervision should be separated. Separation is a current policy issue in the context of the proposed functions of the prospective European Central Bank (ECB). The statute of the ECB (Council of the European Communities 1992) empowers the ECB to conduct EU-wide monetary policy, but leaves the responsibility for banking supervision with the national authorities. The ECB thus seems to follow the German model of separating the two functions rather than the UK model of combining them. To address the separation issue we begin by examining empirically which regime (combined or separated) is less prone to bank failures. However, the regime with the minimum number of banking problems is not necessarily the most efficient in welfare terms. If a low frequency of bank failures was, for example, the result of a tight regulatory and supervisory system, then it is not clear whether a reduction of costly bank rescues would outweigh the potential benefits of a less strict regulatory system. We therefore go on to analyse which regime tends to generate a more efficient resolution of such bank failures while, at the same time, avoiding possible systemic consequences. In particular, we look at the methods of handling a failing bank and the sources of funding used under each regime. Are these methods and funding sources roughly the same for each regime, or are there significant differences in the process of resolving bank failures? Finally, we examine whether bank rescues are financed on an implicit central bank/commercial banks basis, or on an explicit deposit insurance/government basis. So long as rescues and insurance are primarily undertaken by the central bank in conjunction with the commercial banks, then the central bank would also naturally want to undertake supervision. There have, however, been some signs of a trend towards using tax-payers' money for bank rescues which strengthens the case for separation of the two functions and establishment of a government agency for the supervisory function. The paper is organised as follows. In Section 2, we start with a brief account of the historical evolution of the central bank's micro-function (banking supervision) and its involvement in organising bank rescues. In this context, we discuss the role of the lender of last resort and the inroduction of deposit insurance. There is currently a diversity of institutional arrangements, but the