Sustainability reporting aims to inform stakeholders of the companies’ activities within environmental, social and economic issues. The reporting is a tool to increase transparency and it shows the company’s effort to take responsibility and account for its actions. Assurance of sustainability reports is an increasing trend that strengthens the credibility of the reports. There is a risk, however, of management taking control over the assurance process. In order to improve the quality of the sustainability report and its usefulness for the stakeholders, reporting and assurance standards have evolved. The purpose of the study is to describe and analyse the assurance statements of sustainability reports of public listed companies in Sweden. The findings allow the evaluation of how the assurance process influences accountability and transparency. The study is a content analysis of eleven assurance statements from 2010. The findings are categorized and analysed by assurance provider: accountants and consultants.

The difference between the assurance statements were mainly due to the assurance standard used. The assurance statements provided by the consultants were more descriptive and stakeholder oriented compared to the accountants. We highlight the importance of the assurance process’ usefulness and discuss the limited level of assurance applied in the engagements. We argue that, an open and standardized assurance process increases transparency that enables stakeholders to make own judgements whether the company takes responsibility and accounts for its actions. Transparency also creates incentives for the reporting company to be accountable. To increase transparency and accountability, it is essential to involve stakeholders in the assurance process.