One of the most significant social achievements of the twentieth century was the development and implementation of the welfare state concept within the framework of the theory of a democratic, rule-of-law state which ensures the best option for social and economic development, as well as political stability in society. It is proved that although, since the 1970s, some economists, political scientists and lawyers have periodically sharply criticized the concept of the welfare State, predicting its decline, the positive results of its transformation in European countries, as well as the development of the European Social Community within the European Union, show that the welfare State has a chance not only to survive, but also to remain one of the fundamental principles of statehood in democratic countries, and an element of the supranational organization of power embodied in the European Union.The purpose of the article is to analyze the traditional and new challenges to the welfare state which determine the change of approaches to its functioning and priorities at the current stage of development of state-legal and interstate (integration) relations.The key idea that structures the study is the thesis that European states that form a united Europe or aspire to join it, such as Ukraine, despite belonging to the same civilizational community, retain the right to choose how to respond to the economic, social, demographic, migration, environmental and climate challenges of our time. This choice determines the future of national welfare state models. In accordance with the stated goal, the article identifies two groups of major challenges: established (demographic changes, in particular, population aging; changes in the position of women in society and in the labor market; changes in the labor market; poverty and social exclusion) and new (rapid growth of emigration of Ukrainian doctors and nurses; introduction of artificial intelligence technologies; uncontrolled mass immigration; rapid growth of disability in society) faced by the welfare state and, mainly, the social security system, which is its foundation. While the established challenges require adjustments to the priorities and tasks of the welfare state, the newest ones require a significant modernization of the welfare state, adapting it to the new political, economic and social conditions of society.Further research on the selected issues should be conducted taking into account the existence of certain models of the welfare state that unite European states either by geographical (Scandinavian, continental, Anglo-Saxon, Southern European) or ideological (liberal, conservative, social democratic, corporate, solidarity) criteria.The problem of the welfare state's response to the challenges of environmental and climate crises deserves separate development, and in the context of this consideration, the correlation between the social and environmental (“green”) state.