AbstractSociety requires companies to adopt ethical and responsible behavior with regard to environmental policies in order to achieve sustainable development. One of the most controversial sectors in terms of sustainable production is the fashion industry. This study analyzes the extent to which seven of the biggest fashion brands in Spain and around the world communicate their Corporate Social Responsibility (CSR) policies (specifically, those related to sustainability). To this end, we identify the social media platforms used the most by the target audiences for these brands, and apply an exploratory, descriptive methodology to a content analysis of communication about their CSR policies, both formal (corporate websites) and informal (social media). The objective is to identify whether these companies communicate their sustainable activities and practices in the context of their CSR. Our findings confirm that the brands analyzed have integrated sustainability and environmental protection initiatives into their CSR policies. However, although they do communicate this on their corporate websites, they rarely do so on social media. We thus conclude that the seven fashion brands analyzed could make better use of social media to raise awareness and educate customers about environmental sustainability.