This Policy Paper published by Notre Europe aims at shedding light on current discussions on the exercise of solidarity within the EMU. On the basis of a conceptual distinction between two logics, one based on reciprocity and the other based on enlightened self-interest, Sofia Fernandes and Eulalia Rubio review how the issues of solidarity were discussed at the moment of creating the EMU and how solidarity and coordination were practiced before the crisis. Then they analyse the way solidarity has been exercised during the crisis, and identify various factors which have severely hampered the efficacy of the EU solidarity efforts. Grounded on this analysis, they put forward some proposals on the type and amount of solidarity needed to exit from the current crisis as well as to build-up a sustainable and well-functioning EMU in the long term.