During the post 2008 decennium horribile the EU has been faced with unprecedented shocks (the Euro-crisis, the Great Recession and its dramatic social consequences, new security threats, the refugee crisis, Brexit) which have coalesced in a disruptive dynamic of unprecedented scope and depth. Conflicts over sovereignty, solidarity and identity sparked a “deep” political crisis, shaking the very foundations of the EU. Surprisingly, however, the utter collapse of the Union has been averted. In dramatic moments EU leaders agreed on significant institutional advances or at least some backstops. How can one explain this peculiar mix of crisis and resilience? The SOLID project posits that sequences of policy crises tend to disrupt routine policy-making, jeopardize its responsiveness, unleash turbulent forms of crisis politics, and put political legitimacy (even polity durability) at risk. At the same time we also posit that severe crisis situation may also activate polity maintenance incentives for keeping the political community together “whatever it takes”. Covering developments since 2009, SOLID ultimately aims at assessing the overall soundness of the EU’s foundations in the wake of the political crisis. In order to capture both disruption and resilience, we propose to disentangle the “deep” political dimension of the crisis from more policy-specific challenges and analyze it through a “coalition-centered approach”, which we have originally devised for the EU polity. Rooted in political economy, comparative political sociology and policy analysis, SOLID will collect extensive data on processes, conflicts and coalitions through qualitative and quantitative methods, including innovative techniques. A major original survey will also be organized. We aim at providing an original general theory of political crisis, valuable as such, but making a strong impact on the study of EU politicization and its likely (constructive or destructive) outcomes.