The use of the language of environmental justice as a frame for collective action on socio-environmental concerns has now evolved and extended far beyond its original formulation in the USA. This article examines two ways in which the use of the environmental justice frame has globalized. The first involves the international emergence of ideas, meanings and framing processes in new settings around the world. The 'horizontal' diffusion of an environmental justice frame is traced, examining processes of transfer, reproduction and contextualization that are taking place within the political and institutional cultures of different countries. The cases of the UK and South Africa are examined in detail. The second involves the 'vertical' extension of the environmental justice frame to encompass concerns that do not end at national borders but that involve relations between countries and global scale issues such as trade agreements, transfers of wastes and climate change. The implications of these two shifts, the tensions that have emerged around them and their relevance to the pursuit of progressive global social policy objectives are considered.