The achievement of social and economic development involves three processes: the increase in gross domestic product per capita, the reduction of unemployment and increase of employment, the reduction of poverty and income inequalities. Directly related to that are the objectives of new EU member states, as well as other European countries that wish to join the Union and thus contribute to their own development - economic and social. Integrating the new Member States and candidate countries represents a great challenge for the EU, and especially for the social systems of individual countries. The reason for this is primarily a variety of social systems and socio-demographic characteristics of these countries. Because of the strong convergence those can adversely affect their economies, but also the entire Internal Market. With the support of financial instruments and measures that encourage convergence at the national and European level, national social policies contribute to overall economic and social development and economic and social cohesion. Economic convergence leads to social convergence, but not necessarily to the harmonization of social systems. The goals of the paper include the proper assessment of different effects and the dynamics of social (and economic) reforms, which enable a greater level of social convergence, the evaluation of the effectiveness of national social policies and the assessment of the ability of individual countries to adapt to the contrasting demands of social security and employment, and economic growth and development.