To get a loan in the credit union a shareholder must be not only a formally adopted there, but necessary pay in cash contributions, the amount and order of payment of which approved by the General Assembly and fixed by the charter. 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. The relationship of shareholders with credit union are not client-based, they are co-operative, based on different principles and standards, in particular, on the principles of the law of obligations. Credit cooperatives and credit unions exist in many different forms. The main differences relate to the nature of the membership and the opening of a credit institution.