The process of European Integration and creation of the single market revealed many questions and boundaries on the development and improvement of the European Social Policy. Pension?s sustainability has become the priority issue especially during the EU enlargement processes. Different policy instruments and institutions available to governments of Member States in realization of social objectives resulted in a growing diversity of pension polices which produced different combinations of public and private provisions - ?private-public hybrids? , with the state exercising different degrees of influence in their development.