Social workers in health care have been urged to identify the nature of their expertise and to articulate profession specific roles (Peckuconis et al., 2003). This paper reports on the use of a theory of professional expertise (Fook, Ryan, & Hawkins, 2000) in management and clinical practice within two Australian hospital social work settings. This theory, directly applicable to social work, was applied within these hospitals to differentiate levels in social work industrial awards, in staff selection, in supervision and continuing professional development. Specific and broader implications for application of this theory are discussed.