Differences between Family Health Services Authorities (FHSAs) in practice nurse activities are described and interpreted, using the results of postal questionnaires to all practice nurses in England and Wales in late 1992. There were an estimated 15000 practice nurses of whom 12589 (85%) returned a completed questionnaire, which asked about 30 tasks, including domiciliary visits, carried out by practice nurses; employment conditions, professional qualifications, experience, and clinical grading; and practice characteristics. The proportion of nurses undertaking four out of five tasks varied by a factor of two or more across FHSAs. Just over a third (39%) of the variation in nurses' activities could be explained by professional and practice characteristics. The analysis distinguished between FHSAs where nurses were more likely to engage in tasks requiring diagnostic and clinical skills, including assisting with minor surgery, and FHSAs where nurses were more likely to conduct domiciliary visits, help with chronic disease management, and provide advice on welfare benefits, incontinence and health promotion. The former FHSAs were characterized by larger practices with four or more partners employing several nurses, training practices, and practices with a manager. The latter group was characterized by smaller inner city or urban practices, including single-handed partnerships, and practices often employing one nurse. The 1990 general practitioner (GP) contract boosted nurses' involvement in those activities attracting new payments but its impact on their roles and responsibilities was mediated by their professional skills and experience and the type of practice where they worked. The contribution of practice nursing to the delivery of primary and community health care varies considerably. Further research is required to find out whether role diversity reflects uncertainty about the appropriate use of their skills. FHSAs need to develop a variety of strategies to support and promote practice nursing.