Recent research shows the existence of a selective corporate social responsibility (CSR) disclosure strategy that creates a gap between CSR disclosure and actual performance. These CSR decoupling practices compromise the credibility of CSR reports and have triggered a demand for the adoption of credibility enhancement mechanisms, such as adherence to the global reporting initiative (GRI) reporting guidelines, and the external assurance of CSR reports. The effectiveness of such mechanisms is not clear, however. This paper draws on legitimacy theory and addresses the issue of symbolic versus substantive use of assurance, and compliance with GRI reporting standards, by analysing their effect on CSR decoupling using an international sample of 1,939 companies (15,219 observations from 2002 to 2017). Analysis of a sub‐sample of 708 firms (3,730 observations from 2011 to 2017) also shows that the application of GRI guidelines and the specific characteristics of the assurance provider—accountant, experience and specialisation—reduce CSR decoupling practices. The results provide researchers, managers, assurance providers, investors, stakeholders and regulators with additional insight into the value of the external assurance of sustainability reports and have important managerial and policy implications.

In response to recent calls about the need to improve the current understanding of what drives SDG reporting, this paper analyzes the individual and joint effect of a broad array of factors on the integration of the sustainable development goals (SDGs) into the non‐financial information system. Using a sample made up of 1535 international companies for the period 2015–2017, we examine the extent to which both external and internal factors affect SDG reporting as well as the role played by two influential actors in corporate decision‐making (i.e., the CEO and the board of directors) in promoting this disclosure strategy. The results indicate that institutional pressures at the country level, firm size and incentives associated with the monitoring of financial analysts and the demands of investors, together with the specialisation and size of the board of directors are, in this order, drive the level of integration of the SDGs into the non‐financial information system. In the absence of these factors, the training of the CEO in sustainability issues is the main determinant of SDG reporting.