The business of payments and the provision of payment instruments have a rich history, which can be drawn upon in a discussion of standardization. In the middle-ages, for example, the mere existence of a wide variety of foreign and local coins led to a flourishing business of money exchange offices and cashiers in the Netherlands. Malpractices of some of these firms, mostly in the form of physical tampering with coins and alloy, resulted in government regulation on a municipal and province level. Yet, as these type of regulations where hard to enforce, the Amsterdam municipal government decided in 1609 to establish a municipal exchange bank, ‘de Amsterdamse Wisselbank’, originally as a government monopolist. The motivation for doing so was to prevent the regular price-increases of the good coins, to eliminate confusion to the public and to facilitate trade by providing good coins. Later on, in 1621, the regulations were adapted to the actual business practice and private cashiers were allowed – under certain conditions – to conduct business in the city of Amsterdam (van den Berge, 1939, p 34). The example shows us how a diversity of specifications and a diversity of payment instruments, will lead to the development of separate companies which make money by reducing the confusion for their consumers. It illustrates that the abuse of technological know-how and abilities for the sake of increased economic benefits by a few private companies may lead to government intervention for the sake of public interest. Furthermore it indicates that strong market powers may prevail, even in the case of restricted government regulation. As such the example contains all relevant issues with respect to IT-standardization: • can it be assumed that the market will standardize if necessary? • what role should governments play in this process? • does the end-user play a role in this process? In this chapter, I will examine the above standardization issues with respect to the retail payment instruments, developed and in use since the beginning of this century. In this time frame bank notes and coin have been widely available to the public as a basic (and standardized) payment instrument. I will however not include these instruments in this study and limit myself to a study of the standardization of noncash payment instruments that have been available to the consumer. These payment instruments can be seen as the technical means with which consumers effect money transfers to each other. Examples of payment instruments are the forms for credit transfers or in-payments, the debit- or credit cards or home-banking software. It is my opinion that, given the availability of cash an alternative payment instrument, the standardization processes of noncash payment instruments can be seen as the ‘pure’ result of market forces. The study of this process, applied to different types of instruments within one application and industry domain, will hopefully provide additional insight.