Even before the financial crisis, the sustainability of the modern welfare state was in question. An ageing population, rising inequalities, and changing labour markets lead to higher demands for welfare by the electorate, while fiscal constraints and already high levels of social spending in many countries rule out further expansion. Almost all governments do not sufficiently invest in education, training, and child care. While the challenges are mounting, the institutions and financing mechanisms of the welfare state have shown remarkable institutional continuity over more than a century. In fact, the institutional foundations of welfare states adapt only slowly to a rapidly-changing social, economic, and demographic environment. Research in this field includes research about new policy tools for promoting equality, the political preconditions for policy continuity and change in social and labour market policies, the evolution of global social policy, current issues in health and education policy, as well as the role of civil society organizations for social investment.