This paper explores the extent to which corporations currently increase the voluntary disclosures in triple bottom line (TBL) reports. Although research already has provided substantial contributions as to why and how firms apply TBL reporting, there remains limited understanding of the motivations for and against making voluntary disclosures. Drawing from literature in environmental management and accounting as well as international auditing, this work focuses on guidance, boundarysetting and external assurance for TBL reports. An inductive case study approach is applied to investigate the credibility of TBL reporting by contrasting the competing predictions from legitimacy theory and voluntary disclosure theory on voluntary disclosures. A set of firm and industry specific factors are identified that are expected to determine a firm’s level and extent of reporting. The sample comprises nine US and EU red biotechnology corporations which aligned their TBL reporting to the GRI reporting standards in at least part of their TBL reports that were published between 2000 and 2009. An initial attempt is made to systematically investigate the credibility of TBL reporting to develop the model of voluntary disclosures. The empirical findings of this case study suggest that current guidance, boundary-setting and assurance for TBL reports are not sufficient to increase the credibility, comparability and reliability of reporting. Voluntary disclosure theory can serve to provide economic motivations, while legitimacy theory is helpful to provide a legitimating motivation. The findings support the notion that the economics-based factors better explain the secrecy strategy of providing mainly soft disclosures. The increase of disclosure levels maybe is considered sufficient to respond to public pressure. This work concludes by suggesting some directions of research in the areas of boundary-setting and assurance that have academic and practical implications.

This paper explores the extent to which corporations currently increase the voluntary disclosures in triple bottom line (TBL) reports. Although research already has provided substantial contributions as to why and how firms apply TBL reporting, there remains limited understanding of the motivations for and against making voluntary disclosures. Drawing from literature in environmental management and accounting as well as international auditing, this work focuses on guidance, boundarysetting and external assurance for TBL reports. An inductive case study approach is applied to investigate the credibility of TBL reporting by contrasting the competing predictions from legitimacy theory and voluntary disclosure theory on voluntary disclosures. A set of firm and industry specific factors are identified that are expected to determine a firm’s level and extent of reporting. The sample comprises nine US and EU red biotechnology corporations which aligned their TBL reporting to the GRI reporting standards in at least part of their TBL reports that were published between 2000 and 2009. An initial attempt is made to systematically investigate the credibility of TBL reporting to develop the model of voluntary disclosures. The empirical findings of this case study suggest that current guidance, boundary-setting and assurance for TBL reports are not sufficient to increase the credibility, comparability and reliability of reporting. Voluntary disclosure theory can serve to provide economic motivations, while legitimacy theory is helpful to provide a legitimating motivation. The findings support the notion that the economics-based factors better explain the secrecy strategy of providing mainly soft disclosures. The increase of disclosure levels maybe is considered sufficient to respond to public pressure. This work concludes by suggesting some directions of research in the areas of boundary-setting and assurance that have academic and practical implications.