Until proper consensus is reached on what a nurse is and does, any skill mix or clinical role developments will only have limited international relevance, especially in OECD countries. If nursing qualifications are to be valid even across the European Union, then recommended standards such as those of the ICN, must be specified in terms of what different categories of nurses actually can do, and their responsibilities and roles within that scope of practice. Standardization of definitions of categories of nurse internationally should reduce confusion and promote better understanding of patterns of nurse staffing and the effect these may have on patient outcomes.