Empirically informing a European theory of justice is a complex and challenging endeavour, however the emergence of current social crisis, and the resulting inequalities and unfairness, bring about the need to revise the premises that facilitate translation of the theory into concrete guidance to effective social policies and coherent programs and practices. To respond to this challenge, a trans-disciplinary Consortium has been organized to provide a comprehensive series of empirical data, in different ecological levels, in order to understand differences in perceptions of inequality. Through a case study on an extreme expression of inequality and unfairness - LONG-TERM HOMELESSNESS – organized in a multi-method and convergent design, HOME_EU is focused on understanding: a) How much inequality do EU Citizens accept regarding Homelessness; b) How the people with a lived-experience of Homelessness (both present and past) perceive the opportunities, choices and capability gains with the services and the existing social policies; c) What strategies consider the service providers to be more effective in reversing Homelessness; d) How social policies and policy key stakeholders contribute to effectively reverse Homelessness; and e) Develop a generalizable indicator (correlating the different ecological levels of analysis) based on the data gathered by each partner country on the key elements of policy and program efficacy. We believe that with this journey into an extreme situation, we are able to generate translational knowledge about the ecology of long-term Homelessness and contribute towards the advancement of an empirically based EU theory & practice of justice as fairness.