The mutual banking ideas of Proudhon could be adapted to the conditions of modern society, as will be described in what follows. (Note: Proudhon is the definitive source on mutualism, but for those who don't read French, there are the works of his American disciples, e.g. William B. Greene's Mutual Banking, and Benjamin Tucker's Instead of a Book by a Man Too Busy to Write One).

One scenario for an updated system of mutual banking would be for a community barter association to begin issuing an alternative currency accepted as money by all individuals within the system. This "currency" would not at first take the form of coins or bills, but would be circulated entirely through transactions involving the use of barter-cards, personal checks, and "e-money" transfers via modem/Internet. Let's call this currency-issuing type of barter association a "mutual barter clearinghouse," or just "clearinghouse" for short.

The clearinghouse would have a twofold mandate: first, to extend credit at cost to members; second, to manage the circulation of credit-money within the system, charging only a small service fee (probably one percent or less) which is sufficient to cover its costs of operation, including labour costs involved in issuing credit and keeping track of transactions, insuring itself against losses from uncollectable debts, and so forth.

The clearinghouse would be organised and function as follows. Members of the original barter association would be invited to become subscriber-members of the clearinghouse by pledging a certain amount of property as collateral. On the basis of this pledge, an account would be opened for the new member and credited with a sum of mutual dollars equivalent to some fraction of the assessed value of the property pledged. The new member would agree to repay this amount plus the service fee by a certain date. The mutual dollars in the new account could then be transferred through the clearinghouse by using a barter card, by writing a personal check, or by sending e-money via modem to the accounts of other members, who have agreed to receive mutual money in payment for all debts.

The opening of this sort of account is, of course, the same as taking out a "loan" in the sense that a commercial bank "lends" by extending credit to a borrower in return for a signed note pledging a certain amount of property as security. The crucial difference is that the clearinghouse does not purport to be "lending" a sum of money that it already has, as is fraudulently claimed by commercial banks. Instead it honestly admits that it is creating new money in the form of credit. New accounts can also be opened simply by telling the clearinghouse that one wants an account and then arranging with other people who already have balances to transfer mutual money into one's account in exchange for goods or services.

Another form is that associated with LETS systems. In this a number of people get together to form an association. They create a unit of exchange (which is equal in value to a unit of the national currency usually), choose a name for it and offer each other goods and services priced in these units. These offers and wants are listed in a directory which is circulated periodically to members. Members decide who they wish to trade with and how much trading they wish to do. When a transaction is completed, this is acknowledged with a "cheque" made out by the buyer and given to the seller. These are passed on to the system accounts administration which keeps a record of all transactions and periodically sends members a statement of their accounts. The accounts administration is elected by, and accountable to, the membership and information about balances is available to all members.

Unlike the first system described, members do not have to present property as collateral. Members of a LETS scheme can go into "debt" without it, although "debt" is the wrong word as members are not so much going into debt as committing themselves to do some work within the system in the future and by so doing they are creating spending power. The willingness of members to incur such a commitment could be described as a service to the community as others are free to use the units so created to trade themselves. Indeed, the number of units in existence exactly matches the amount of real wealth being exchanged. The system only works if members are willing to spend and runs on trust and builds up trust as the system is used.

It is likely that a fully functioning mutual banking system would incorporate aspects of both these systems. The need for collateral may be used when members require very large loans while the LETS system of negative credit as a commitment to future work would be the normal function of the system. If the mutual bank agrees a maximum limit for negative balances, it may agree to take collateral for transactions that exceed this limit. However, it is obvious that any mutual banking system will find the best means of working in the circumstances it finds itself.