Specialization of credit unions to provide financial services to its shareholders requires a particularly strict regulation of membership and acceptable activities. To reduce the risk of default on loans members of the credit union shall the joint guarantee. 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. Taking a decision to join a credit union, citizens create an organization through which they participate in the shared savings by mutual crediting and joint (collective) use of personal savings. The relationship between credit unions and shareholders arise from the membership and are not customer relationship. Credit unions are financial institutions, financial cooperatives of citizens, and in this capacity they are above all associations of people, not unification of capitals, which is typical, for example, for public companies. Credit unions historically formed as a special form of social support, initially taken upon themselves the social mission of protecting the interests of citizens in the field of financial services. Credit union as a consumer cooperative operates on the principles of equality of all its members. Worldwide credit union movement is represented by regional confederations and national organizations within the World Council of Credit Unions. Corporate alliances are intermediaries between credit unions and financial markets.