This paper discusses the repertory grid technique, from its development by George Kelly as a means of demonstrating cognitive/perceptual systems in individuals, as postulated in his Personal Construct Theory, to its use in studies in nursing and social work The original concept having focused on the uniqueness of, and differences between, individuals' perceptions of the world, in recent years it has been applied to the examination of characteristics within groups The theoretical basis for this is discussed, with reference to a selection of studies of nurses and social workers, including a small comparative study of psychiatric nurses, general nurses and social workers The degree to which the findings of these studies may be generalized is discussed In retrospect, some of the applications are considered to be outside the paradigm of the Personal Construct Theory which underlies the repertory grid technique