This paper examines the role of various boundaries in giving both professional groups and individuals a sense of identity that provides both with status and legitimacy. Close attention is paid to the boundaries between personal and professional identities and values. Sociologists working with a discursive approach argue that professional identity and status are achieved through the rhetorical presentation of certain values and responsibilities as personal, and therefore outside the boundaries of professional practice. This paper takes this argument forward, by arguing that in particular contexts, certain kinds of values are consciously articulated as personal and incorporated into the defence of professional legitimacy. Bringing personal claims inside professional boundaries is further evidence of the fluid and negotiated quality of the boundary between personal and professional values and notions of self. The paper consists of a discussion of the construction of professional boundaries, professional involvement in risk, issues raised by antenatal screening and analysis of a study of a group of professionals involved in antenatal screening. The paper explores the circumstances within which even senior professional groups and individuals look to representations of the personal self as a defence against critiques of their professional practice. Where the risks that professionals generate and interpret are medically ambiguous and socially contentious the abstract professional and medical framework is insufficient and other rhetorical values become resources in securing the professional role.