This article examines the extent to which issues of environmental sustainability are represented in three national social work codes of ethics – the United Kingdom, the United States and Australia. These national codes are discussed and implications for social work are analysed with a view to strengthening the profession’s position regarding environmental sustainability. Findings suggest that national codes do not include concern for environmental sustainability as a core professional concern. The authors make recommendations for developing ethical practice and further argue that the international professional body of social work, the International Federation of Social Workers (IFSW), should take a fundamental leadership role in advocating for environmental sustainability.