Using primary nursing as a 'case study', this paper reviews research literature which attempts to measure the effectiveness of a mode of nursing using outcome measures. Previous research, it is argued, is hampered by a lack of conceptualization of structure and process and inadequate research design, with consequent uncertain findings. A shift in emphasis is suggested from an evaluation of global concepts, such as primary nursing, to an identification of the features of structures and processes of nursing care which interrelate with patient and nurse outcomes. For this purpose, multivariate research design and investment in methodological research are recommended.