This Working Paper is the result of a workshop held at the European University Institute in November 2010. At the heart of it lies a reflection on the potentialities of a new legal concept : social environmental justice. Building on the longstanding tradition of social justice and the more recent trend of environmental (or ecological) justice, our aim was to discuss how these two different dimensions of 'justice' overlap and could be reconciled in an all-encompassing notion. Moreover, we discussed the need for such a new concept in the light of the contemporary challenges of climate change and economic globalisation and focused especially on the concept's added value compared to the already existing notion of sustainable development. In addition to that, we explored the practical value of social environmental justice especially in the context of legal practice. This publication is a mirror of the different normative approaches (more social, more environmental, more holistic) one can adopt in dealing with problems such as climate change and globalization. Finally, it suggests different legal paths (Human rights, Private International Law, European Law) that could be taken in order to address these issues. Table of Contents : Social environmental justice : from the concept to reality / Antoine Duval and Marie-Ange Moreau -- Social environmental justice : the need for a new concept / Marie-Ange Moreau -- Sustainable development without social justice? / Dominic Roux and Marie-Claude Desjardins -- Sustainable development... without 'ecological' justice? / Sophie Lavallée -- Realising social environmental justice : human rights, sustainable development and possible ways forwards / Emmanuela Orlando -- Corporations and social environmental justice : the role of private international law / Claire Staath and Benedict Wray -- International human rights in an environmental horizon / Francesco Francioni