In co-operation with our partners the Friedrich Ebert Stiftung and the Hans Böckler Stiftung, we explore the issue of ‘just transition’. This idea has evolved, in a sense, as a sub-set of the Green New Deal. Making the ecological transition to a sustainable future is essential. From a social-democratic perspective just transition needs to be implemented in a way that does not further increase social inequality. Otherwise it will have negative social side-effects, particularly in terms of lost jobs in fossil-fuel industries and fuel poverty for the socially excluded. This dossier elaborates what ‘just transition’ means, from the concept itself to its outworking on the ground. It includes contributions from the Spanish deputy prime minister and minister for the ecological transition, from leading figures in the trade union movement in Europe and internationally and from the director of the European consumer organisation.