The aim of this study is to analyse how secondary stakeholders influence managerial decision-making on Corporate Social Responsibility (CSR) disclosure. Based on stakeholder salience theory, we empirically investigate whether differences in environmental disclosure among companies are systematically related to differences in the level of power, urgency and legitimacy of the environmental non-governmental organisations (NGOs) with which these companies are confronted. Using proprietary archival data for an international sample of 199 large companies, our results suggest that differences in environmental disclosures between companies are mainly associated with differences between their environmental stakeholders’ legitimacy. The effects of power and urgency are of an indirect nature, as they are mediated by legitimacy. This study improves our understanding of CSR disclosure by demonstrating that, next to the well-documented effect of company characteristics, stakeholder characteristics are also important. Besides, it provides scarce empirical evidence that not only primary stakeholders, but also secondary stakeholders are influential with regards to management decision-making. And more specifically, it offers insight into why some stakeholder groups are better able to influence disclosure decisions than other. The results also have important practical implications for managers of both environmental NGOs and large companies. For managers of environmental NGOs the results provide evidence of the most successful tactics for having their environmental information demands satisfied by companies. For company management the results provide insights into the most important stakeholder characteristics, on the basis of which they may develop strategies for proactively disclosing environmental information.