Exchange-rate flexibility covers a multitude of sins and of virtues. My main purpose in this paper is to catalogue the various forms of sin and virtue and to comment as objectively as is possible upon the merits and demerits of each form. But I will not disguise the fact that I am one of those who favour a much greater measure of exchange-rate flexibility than is practised by the countries of the free world today. Accordingly I shall arrange my paper in the following three parts. First, I will outline the reasons why in my view we need to consider very seriously the adoption of a greater measure of exchange-rate flexibility. Second, I will catalogue the various forms which exchange-rate flexibility can take and will note the arguments for and against each form. Finally, I will describe the form of exchange-rate flexibility which I would personally advocate in present circumstances and will try to put it into the framework of the present discussions on the possible reform of the International Monetary Fund.