This paper explores the apparent paradox that while public sector auditors have become more powerful by claiming performance auditing expertise and linking this to New Public Management reforms, the same reforms have provided an opening for competition between private and public sector auditors. In Denmark, the competitive relation has led to a jurisdictional dispute between public and private sector auditors in which the former have developed a special qualification for public sector auditors. The paper analyses the development of this qualification using Abbott's (1988) theory of the system of professions, thus focusing on how the involved groups have attempted to build networks of support for their competing jurisdictional claims of expertise. The case contributes to knowledge about the potential for development of a distinct public sector auditor identity. The case suggests that to develop such an identity and gain professional recognition, public sector auditors need to convince parliaments, standard-setting bodies and universities that a public sector auditing qualification serves as a solution to some of their problems, too.