Purpose – The purpose of this paper is to show how a major public benefit entity in New Zealand uses formal accountability mechanisms and informal reporting to justify its existence. The paper is premised on the view that the accountability relationship for public benefit entities is broader and more complex than the traditional shareholder-manager relationship in the private sector. Design/methodology/approach – This longitudinal single case study of the Department of Conservation (DOC) spans the period from its establishment in 1987 to June 2006. It involves the detailed examination of the narrative disclosures contained in the annual reports, including the Statement of Service Performance, over the period of the study. A number of controversial items that appeared in the printed media between 1 April 1987 and 30 June 2006 were traced through the annual reports to establish whether DOC used impression management techniques in its annual reports to gain, maintain and repair its organisational legitimacy. Findings – The analysis found that the annual report of a public benefit entity could play an important legitimising role. Using legitimacy theory, it is argued that assertive and defensive impression management techniques were used by DOC to gain, maintain and repair its organisational legitimacy in the light of extensive negative media publicity. Originality/value – This is one of the first studies to examine the relationship between narrative disclosures in annual reports and legitimacy in the public sector. The paper provides a valuable contribution to researchers and practitioners as it extends the understanding of how public benefit entities can make use of the narrative portions of the annual report when pursuing organisational legitimacy.