The institutional environment for corporate social responsibility (CSR) disclosure worldwide is still predominantly voluntary and unaudited, with few studies exploring the validity of information disclosed in CSR reports (Ingram and Frazier, 1980; Holder-Webb et al., 2008; Chen et al., 2016). Researchers frequently argue that CSR disclosure enhances legitimacy by reflecting a genuine commitment to social responsibility (see, for example, Ullmann, 1985). CSR reporting might, however, be motivated by managerial self-interest (Kim et al., 2012) and the need to window dress or to greenwash, which can involve the use of false or misleading information to present an environmentally responsible image (Griffin and Weber, 2006). In such cases, voluntary CSR disclosure would tend to be biased towards the strengths of a firm’s CSR performance, while information of potential concern to the public might be withheld (Chen et al., 2012). Concern over the credibility of voluntary CSR disclosure has attracted researchers’ attention since the early 1980s. A number of studies find that firms’ voluntary CSR disclosures do not always correlate with actual CSR performance (Pattern, 2002). In a multi-country study investigating voluntary assurance of CSR reports, Simnett et al. (2009) demonstrate a strong link between companies with a higher need to enhance credibility and those having their CSR reports assured. They also find that companies operating in stakeholder-oriented countries are more likely to choose the auditing profession as an assurer. In the most recent study examining the credibility of voluntary CSR disclosure, Chen et al. (2016) used the US data to investigate whether firms’ commitments to independent financial statement verification (auditing) increase the credibility of their voluntary CSR disclosures. In other words, Chen et al. (2016) use firms’ investment in the assurance of their financial information quality, proxied by higher audit fees, to signal a higher level of credibility of voluntary CSR disclosure. The proposition of Chen et al. (2016) is based on the idea that firms adopting voluntary CSR reporting will also demand a higher level of audit assurance for their financial statements.