Among the U.S. credit unions, there are three groups that differ in terms of assets, shareholders, and business services. Until the 70's there was a proliferation of the U.S. credit unions due to the increase of their number and the number of shareholders, although it must be acknowledged that there was also and a qualitative growth. As of the January 1, 2012 the national associations and confederations unite more than 196 million members participating in the 51,013 credit unions in 100 countries. The specifics of credit unions and, in some sense, their uniqueness lies in the fact that they work not for profit and do not appropriate profit. A potential new member of a credit union must submit a recommendation of shareholders in which the referee becomes a warrant of a future member of the credit union.