The European common currency, the euro, is in crisis. Bad news about indebted governments and economic recession has continuously outperformed itself since 2009/2010 and kept the European Union and its member states in suspense. It is up to them to combat the crisis. This master thesis deals with the European sovereign debt crisis (“euro crisis”) and tries to allow a better understanding of how the crisis has been managed by governments at the European level. A special focus is put on decision-making in the crisis, posing the research question “How can the decision-making of the EU in the euro crisis be understood?”. To solve this research problem, three different approaches are applied: liberal intergovernmentalism, historical institutionalism and cognitive institutionalism. Each of them adds different aspects to the analysis, gives answers from its respective point of view and thereby widens the overall picture that evolves. The design of the thesis is a case study with the euro crisis as a special case of decision-making and crisis management. Official documents and statements, expert interviews, scholastic, expert, and journalistic analyses are employed as basic research material. It has been uncovered that, powerful states, especially Germany and France, have bargaining advantages during crisis decision-making. However, the decision-making is constrained by institutional aspects (rules, norms and values). Stress factors deriving from the crisis situation facilitate group dynamics that appeared at least partially during the ongoing crisis.