The overall purpose of this licentiate dissertation is to advance our understanding of the auditor by creating a concept of the auditor through focusing on auditors' own perceptions and understandings of their work in relation to boundary-setting forces. The audit profession, the audit firm, the client, society, regulations, and the market are all boundary-setting forces that influence the work of auditors and how auditors perceive and understand their work. The concept of the auditor consists of who the auditor is and what the auditor does; this concept is shaped interactively by the boundary-setting forces, that exist in the auditors' environment and by the auditors themselves, through the view auditors have of themselves and their environment. The boundary-setting forces have in recent decades undergone significant and rapid changes; for example, increased commercialization as well as significant regulatory changes, which are expected to have influenced the concept of the auditor. The concept of the auditor therefor needs to be explored to understand who today's auditor is and what today's auditor does.